Value of grouppo depends. I bought a group last year for $135 (shipped). it came with a frameset and wheels/bars attached.
the headset and bottom bracket and crank accoutrements ( dust caps and bolts ) are very valuable and might fetch $80. brakes might fetch $80. all the rest all put together might fetch $80.
if you sell it all together, probably sub-$200.
I love my trek 510, it rides just great. i hate those campy pedals, which slip like crazy when it rains. some crooked bikeshop had already stripped the dust caps and crank bolts, though, on my bike.