You can get a Pinarello Gan with 105 for $2500.
There are Dogma F8 frames for less than $3500 right now at R&A Cycles. Throw on a set of last year's Shimano C24 wheels for $750 and an Ultegra group, swap in bars and saddle from your old bike and an enterprising cyclist could have one for $5k. I thought about buying one of the frames and just porting parts from my current bike.
I can't remember where but someone had Dogma F10 frames used at trade shows and dealer demo/display for under $4000.
-Tim-