One would have to see the ad, but I don't think I'd pay $1800 for the bike either. Asking price doesn't always equal selling price.

It is hard to tell how Bicycle Blue Book valuates the used bikes. I have a feeling that they take the MSRP and applies a time based depreciation algorithm.

Unfortunately, not all bikes will depreciate uniformly, and location is also important.

Titanium bikes are still relatively rare, and in good demand, so there may be a bonus that isn't accounted for with Bicycle Blue Book. Wheel upgrades? What version of Ultegra?

I could imagine the bike going for between $800 and $1200. Yeah, a bit of a range.