I bought an older Trek 2200. It's a carbon tube/alum lug model
I've been on the lookout for a decent 56cm bike for the better part of 6 mos. but everything was $750 plus. I also had a price limit of $500. Mrs. tmshokie wanted to be sure it was not a "fad" so I had to prove my faithfulness on a reasonable bike.
After buying it (a little under $500) I've seen them go for $400. It's decent. 105 grupo, shimano wheels, carbon forks and seat post, cat eye and tri bars. Biggest issue is the age of the frame. Thought it was a 1999-2000 at purchase. Did not do my homework. Looks to be in good shape overall, for a 18 yr old frame.
I read all the noodly comments on here with these frames but I'm 5'11 and about 175. Apparently I don't have enough harumph! to get it to noodle yet. Rides very smooth for me, compared to the all alum Trek I was borrowing.
On a better buying note I got some Specialized carbon shoes, Look cleats, two LG helmets, 3 Performance Bike jerseys, 2 pair chamois riding shorts, mini pump and saddle bag ALL for $75 off CLL. All basically brand new. Maybe used 2-3 times. But I missed out on the Madone that the guy sold for $1200 that was $3000 new. Soooooo close.