I just bought my Graphite 6 speed Roadster with 45,000 miles on it for $12,200 - yours better be damn impressive!
In fact...
My Red one is an 05 with 33,000 miles in showroom condition, (I even dust the engine off once a month) in the dead of SUMMER the best offer I had was $14,780 ($14,000 plus $780 for the new tires). If I'm offered that this summer, I MIGHT take it.
Only CarMax can get $20,000 for a Non-SRT Roadster. (Not attacking you, just saying.)