it really depends on how handy you are around bike.
you can get a smoking deal on a used bike but they almost always need small adjustment, parts vs a new bike.
The TCR C1 is carbon, right? the frame alone can sell for $450(c1 is the same as c0, which is the top of the line TCR back then, frame wise it's the same with different color/graphic)
taking measurement will not tell you anything more than a good starter range, test ride is a must.