Welcome to the forum. We have a PDI (Pre Delivery Inspection) checklist located here:
http://www.keystonerv.org/forums/showthread.php?t=5129
Print it out, read over it and take it with you when you go to look at the Sprinter. The checklist will guide you through all the systems and components so you are sure not to miss anything.
Good Luck with your new RV.