I may not be the best person to answer this question, because I am not currently in the expediting business. But, that being said, I have done quite a bit of research on the issue. So, I will take a stab at it . . . I know if I quote something wrong someone will quickly correct my error!
The correct answer is that there is no real answer to your question . . . this is because there are too many contingencies and variables and each contingency can expect a variable pay rate. The easy answer is read this website and look at each company carefully.
But, that is not what you asked . . . So, here goes:
First - What company will you be working for? Each company pays a different cpm. Within that cpm, there are different rates based upon your years of service and experience level.
Second - What type of truck will you be driving? Van? Straight Truck? Semi? Each pays at a different rate.
Third - Company Driver, Lease Operator, or Owner Operator? Each pays, again, at a different rate. If you are a Company Driver the company takes all the liabilities. If you are a Lease Operator you split your pay (usually 60/40) with the lease owner and he pays for repairs, etc., whatever the lease agreement says. If you are an Owner Operator you get the best rate of pay, but are left with all the liability and maintenance - if prices go up you take the hit.
Fourth - Now you know who you are driving for . . . what you are driving . . . and how your ownership is . . . You are on the road and driving - Are you driving long-haul (3 weeks cross-country), short-haul (home every weekend) or something else? Do you get paid lay-over? Dead-head? Etc.? What if you get sent to some obscure place to pick up a load and the load isn't ready for 3 days - and there are no other loads for you to take in the area? You're not making money if your wheels aren't turning. A company driver will get the load first, because no matter what if a company driver sits it costs the company money. From there Lease Operators and Owner Operators split the rest.
The best advice I got on this was from a driver that said "Most companies are about the same", (it will be up to you to sort out the bad ones and there are bad ones), "once you pick the companies you would like to work for . . . then its just a matter of looking at their benefits package."
So, brush up on your spreadsheet abilities and start doing your homework. In the end, the research you do now could make or break you, so doing a good thorough research can never be under valued.
Best of luck to you.
Mypie