$12,500 reasonable for a TT500.. What are you smoking??!!
I guess a good clean TT500 is worth about the same as any other mint NOS VMXer.
You couldn't build it for much less than 10K.
I was thinking about values, I guess 20-30K buys factory bike RH/OW
15-20K buys highly desirable CCM/ G80 Rickman
10-15K buys 2nd level highly desirable MC490/ Foxy CR, Mugen/HL
10K mint production MXer .... lots of NOS and trick parts, mint original
5K ....tidy comkon or garden production, RM400, YZ465 etc
Under 5K.... normally bikes that will soon be well over 5K.