We purchased a 2006 Sportsmobile Sprinter van and currently have 93,000 miles on it. We have had 2 problems - the turbo resonator failure common to that model Sprinter and we also needed to replace the EGR valve (under warranty). If you buy a pre 2007 Sprinter make sure that the turbo resonator has been replaced or else have it replaced. There is an aftermarket replacement that is reliable, but you will have to search this site to get the specifics.
Service costs don't seem that much out of line - certainly not the $1000 quoted by one respondent - but the engine does take 9.5 qts. of synthetic oil which is a little pricey. Our Sprinter came with the "Assyst" option which calculates when you need service based on how the van is driven. We generally run about 14,000 miles between oil changes.
Our van is a custom conversion done by Sportsmobile in Texas. When we compared the floor plans available on the Ford/Chevy platforms to the Sprinter we found that the Sprinter platform was far more versatile than the others and this was our primary reason for choosing the Sprinter.