Don't underestimate what you might be able to get one of those boats for! I found an almost new (dealer demo) epic 22 with less than 80 hours that I was working the final details with my family, and it went for 8K less than what they had it listed for. The guy that bought it was from Malaysia and had it shipped (literally) overseas.
The nomeclature is like this: Epic 22 and X22 are direct drive and S22 and SX are v-drive. All '22's' are bow-rider boats. X22 and SX are decked out with wakeboarding goodies like tower, ballast tanks, etc. The Epic 21 is a closed bow tournament class ski boat with a 19.5' running surface.
Here's a picture of the SX (the other one I posted was an S22). You can see the difference.