$5800 - (selling it for exactly what I owe). It cost me 7600 a year and a half ago before taxes. 

For Sale:  20' Interstate Enclosed (Car Carrier) Trailer.  Trailer is 1 1/2 years old, purchased before the 2011 season from Trailers Plus.   Trailer interior has been painted white and floor painted gray.  It's like new. Trailer has rear ramp door.  I can fit my 600 in the trailer with the wing on the car while it's lowered, a pit cart, and a quad with no problem.  I've also had two complete cars in this trailer with my pit cart.  Trailer tows awesome! 

Trailer has lockable side door, diamond plate runners, Ez lube hubs with grease caps, LED tail lights, interior lights, rear load lights, full size spare, interior has been pained white and gray.   This has the 10,000 lb torsion axles, (not the cheap spring axles) and this trailer tows perfectly.  Everything works.