Is that a 3" barrel? Interesting. Some guys really like the 3"s.
If it was a 4" barrel, we could pin down the cost very well, as CDNN and J&G and such places have a lot of those for sale at extremely good value prices -- between $250 and $300. Security company trade-ins. They pretty much all have bobbed hammers, and some may be truely converted to DAO.
A 3" gun should bring a bit more, I think, just because they're a little less common.
If the trade value was somewhere around $300, I'd be jumping on that.