Well, the EGR valve problem on the Sprinter has been solved with the redesign of the 2004 and later models, but that's not to say that the EGR valve is now any more bullet proof than an EGR valve in another vehicle. The Sprinter is not the only vehicle to have an EGR valve go bad.
Most EGR problems with 2004-2006 Sprinters can be solved by taking the valve off, cleaning it out with brake cleaner and a brush, then putting it back on. Or, in the case of failure, buy a new or low mileage used valve on eBay and replace it yourself. The list price on the EGR is $437 (and is what you'll pay at a dealer), but can be had for for $330 from Europarts, half that on eBay (or there is often one taken from a wreck with few miles on it for well under $100 on eBay).
Most dealers charge in the $95 an hour range for labor, some are higher (Dallas Dodge OMG), and many will charge at least the MSRP for parts. The more maintenance and repair you can do yourself the better off you will be. I have essentially no automotive maintenance or repair experience, and am not mechanically inclined, yet there are a lot of things I can do on this Sprinter. I change my own oil and filters, fuel filters, engine air and cabin air filters. I save a ton.
The center knob on the AC control panel is connected to cables that operate doors that control the airflow to the dash, floor and defrost. It became nearly impossible to turn, as the doors and cables needed to be lubed. I checked, and "book" labor for that is 3 hours, and involves removing several chunks of the dash console to get in there to the cables and doors. Did it myself and saved $300. It was a PITA, but it only took a couple of hours, and I didn't break anything. Yes, I am very proud of myself.
Had a problem a few weeks ago with the AC blower motor going bad. To have it replaced at a dealer is a little more than $300. I removed the motor, cleaned it, lubed it, replaced it, and it's working fine. A dealer would have replaced it without question.
I'm not comfortable with draining and flushing my transmission, or the rear end, so I have my dealer do that. The transmission and rear end at a dealer will cost about $450 (if they want much more than that, laugh at them and go somewhere else, as even Dallas Dodge OMG doesn't charge much more than that), and needs to be done every 60,000 miles or so. That's a lot. For a complete flush and renew, it takes 12 quarts of transmission fluid, of which most dealers charge about $20 a quart for. Europarts has it for $12.95, which cuts the $450 down to $366. I get mine off eBay, there's a guy who sells it 6 quarts at a time for what ends up being about $7 a quart. Buy 6 here, 6 there, then I'm ready for the service. Had it done last week, saved $150 by supplying my own fluid. (Incidentally, it is recommended that you do not change the trans filter until you get into the 250,000 mile range, about the 4th service, rather than at each service. Apparently changing it out too soon causes more problems than it solves.)
The only problem I'm having is a chronic failure of the serpentine belt tensioner. Those should last at least 200,000 or 300,000 miles, but I've replaced mine 3 times in the past 14 months. First one was replaced at 58,597 miles, along with an idler pulley, then that one had to be replaced 129,620, just 71,023 miles later. Then, 16440 miles later I had to replace a water pump pulley, and hoped the bad pulley was the cause of the tensioner failures. Nope. At 154,994, a mere 25,374 miles after the previous one was replaced, I had to replace it again, along with the idler pulley again.
The tensioner is dealer priced at $179 and the idler pulley is $79, and if you need a serpentine belt that's another $50 or so. It adds up, especially when you add in the 3 hours labor, to where you're in the $600 range by the time you add in tax and the ever-popular shop supplies charge. And a belt tensioner replacement isn't exactly something you want to do on the side of the road (at least I don't). I do carry a spare belt with me ($25 from Europarts), but it's getting to the point where I need to order a spare tensioner ($90 from Europarts) and a couple of pulleys ($25 from Europarts) just to keep on hand. I might or might not do the repair myself, but at least I'll have cheaper parts on hand for whoever does it.
When it fails, it's out of alignment, and needs to be replaced. What's causing it to go out of alignment, no one knows. I can replace a thrown belt, but being out of alignment, it just throws it immediately again. And because it is out of alignment, it wears one of the idler pulleys unevenly, too, so that has to be replaced along with it.
My Sprinter tech at home took a look at it and can't see a reason for the failures, and he hasn't seen a large number of failures in other Sprinters, nor has he heard of such chronic failures from other techs. He had the parts guy check the national database and it showed a very low incidence of failure nation-wide, so I dunno. It has such a low failure rate than only the larger Sprinter dealers will stock a replacement tensioner, others can get it the next morning from their distribution center. My dealer at home is a small one and doesn't stock it, and to date, they have never ordered one.
Turbo resonators are another story. My tech said he's shocked that I'm still on my original resonator. Said he's replaced those so often than he can do it blind folded now. It's interesting that the vast majority of the time he replaces the OEM resonator with the after-market one-piece aluminum Turbo Resonator Eliminator
Info here.
Maintenance on a Sprinter can be very expensive, especially if you let the dealer do everything. But routine maintenance is critical, and you can save a lot by doing as much of it yourself as you can. Even the routine maintenance is expensive, like oil changes, but it's not really that bad when you factor in that you don't need to do it as often. You can save a lot of money by supplying the dealer with the fluids and parts needed for maintenance, like the transmission fluid, for example. You can do a lot of preventative maintenance, like cleaning and lubricating the blower motor and the EGR valve, before they fail. Changing out the engine coolant at 100,000-150,000 miles instead of leaving it in there until the radiator needs replaced due to corrosion.
One that I've been doing, and my tech confirmed, is to use an injector cleaner and water dispersant (like Howes Meaner Power Cleaner), in every tank. He said that's one of the simplest things you can do to prolong the life of the injectors ($400 a pop, plus ridiculous labor, just ask OVM about that). Dirty injectors increase the pressure, which not only allows water damage to occur to the injectors if a dispersant isn't used, it erodes the injector cooper seals which causes a very hot blowby and literally cuts into the head like a torch. My tech said copper seal failure is not a high percentage of incidence by any stretch, but it's real nasty, and real expensive, when it happens. But he did say that premature injector failure and replacement was higher than it should be, simply because people don't change their fuel filters often enough, and/or they don't use a good injector cleaner on a regular basis. Said that if you don't use something like Howes, then change the fuel filter like clockwork at 10,000 miles, otherwise you can go about 30,000 between changes if you use a cleaner/dispersant.
So, the key to maintaining a Sprinter is regular maintenance, good preventative maintenance, and smart maintenance. But that's true with any vehicle, I guess. One thing to do is find a good Sprinter tech that will answer questions. Find out which parts tend to go bad at x-miles and replace it before you get to that point. Of course, that's not just for Sprinters, but for any vehicle. If starters tend to go bad at 300,000 miles (and I have no idea what the real number is), replace it before you get to the point where it fails. Serpentine Belt is a good example. Unless you carry a spare with you and are prepared to change it on the side of the road in the dark while under a load, replace it at 100,000 or so, even if it might last 150,000 or longer. A $25 belt replacement will cost you far less than will a tow and a dealer replacement, not to mention the probable loss of load revenue. Replace hoses before they crack and fail, and most of those you can do yourself for far less than at a dealer.