You can get 1st gen CTS-V's for around 15k.. About 4 months ago I sold my 05 black/black with 94k miles for 15k..
If you're looking for an 04 or 05, be sure to find one that's had the newer style diff installed, other than that they're great cars! The interior isn't the greatest, but you will VERY EASILY forget about that when you mash the gas or the brakes.. The handling is fantastic, and the drivetrain is pretty bulletproof, assuming you have the updated diff.
Did I mention you can get 25MPG highway EASY?
1994 Infiniti Q45- First 5-speed swapped Q45.
2007 BMW M Coupe