Sprinter repair costs can be significant, particularly when compared repair-for-repair, side-by-side with Fords or Chevy, but that's short-sighted and doesn't take the big picture into account, namely, Total Cost of Ownership. People look at the cost of a tranmission, while completely dismissing the money saved on fuel economy, for example, and think Sprinters cost more than Fords to operate. They don't, at least not for most Sprinter owners. You hear horror stories because non-horror stories don't get your attention, but horror stories do. I've heard horror stories for every vehicle out there.
Having said that, if you let a Sprinter dealer do all of your maintenance, you're gonna get hosed big time, like a $427 oil change (which (probably) also includes regular "maintenance" things that get done as part of the regular maintenance schedule). Buy oil and filters, including air, cabin and fuel filters, online and do that yourself. Changing the oil in a Sprinter is so easy a caveman (or an 8 year old girl) can do it, especially if you replace the drain plug with a Fumoto Oil Valve. I've ordered brakes and rotors and many other parts much cheaper online than paying MSRP (often marked up more than that) at a dealer. Some dealers are clearly untra-proud of their work, like Dallas Dodge who wanted to charge me $850 to replace a belt tensioner. Others will do the job for half that. If you buy the parts online you can get it done for half that again.