I've been looking for a CAAD9 to replace my R3000 CAAD4, but I came across a 2006 Six13 with a handfull of rides on it. It's full Dura-Ace with Kysium SL3 wheels. I think I could get it for $2800. Value-wise, is this a good deal?

Well here are the break down :

Mavic SL3 you can buy it from Ebay for $650, Dura Ace grouppo for $1200 and the final cost for the frame is $950 and presume if you are getting a team frame not pro version. If budget is OK why not go with System Six Ultegra setup for now and upgrade it at a later time. That is my 2 cents.

By the way you can get a S6 frame around $1500 at LBS.