Have: Surly Cross Check, 54cm. Can be offered as complete bike or just the frameset. Barely ridden at all. I built this myself, including the wheels, and it is in tip-top shape. It's unusual.

I am not offering the fenders or front rack.

I can reconfigure the bike within a few constraints.

700c wheels with CR18 rims
35mm Panaracer Pasela tires
Sturmey Archer drum brake front hub
Shimano "roller brake" rear hub with 8-speed cassette
Shimano RSX crank
Shimano 105 derailleurs
Shimano 9-speed bar-end shifters
Nashbar mustache handlebars

This is a heck of a solid bike. The brakes won't need maintenance for 20 years or more, and they don't care about weather.

I'm flexible as to what I want in exchange. Maybe a lighter bike, or maybe even something that's not a bike.