Here's a early "beater" that's been reblued over the rust pits. I'd still not sell it for a penny
under $500. An "original" in poor condition is worth more, IMHO.
The Flatgate Single-Sixes were made in 4 variations. The guns under s/n approx. 2000 carry the highest value.
As with the Flattop, the exact condition weighs heavily on the value.
Good digital images posted here or on the Ruger Forum will certainly help we collectors to discern your guns' values.
flatgate