Any quality new Class C should need absolutely nothing right off of the showroom floor with the possible exception of proper tire inflation and perhaps an alignment... both of which are the dealers fresponsibility. If it needs anything else it is the wrong Class C... keep shopping.
Think of it this way, would you spend $100,000 or likely much more on a nice Mercedes, BMW or Range Rover SUV if the salesman said "Well it will need a couple of thousand dollars worth of suspension improvements, an alignment and the tires need to be properly inflated"??? :S
A serious, think 1 hour minimum test ride in a wide variety of road conditions to include some freeway time {see how it responds to passing trucks and how much fun merging is or isn't} should be a nonnegotiable condition of sale. If after making your best deal the dealer balks at the test drive Run Forrest Run! Go find a dealer who is willing to earn your business.
As always... Opinions and YMMV.
:C