I bought a used SR9 with stainless/polished slide and three mags, I think it was on this forum, for $350 shipped.
The trigger was one of the early ones, and kinda crappy. Added the Ghost Products trigger which made a profound change to (and improved) the trigger.
It's a fine gun, and well worth what I have in it. (Mine came with a holster that I sold for $35...)
I understand that the SR9c trigger is much, much better -- and laster versions of the SR9 apparently have the improved trigger, too.
I think it is like a more-user friendly Glock 19 -- but with more pieces. (I think there are more parts in the firing assembly (striker, safety, etc.) than in the entire Glock gun.)
If its got a good trigger, $350 seems reasonable. (I spent $20 for the Ghost Trigger connector parts, and $45 to get a local gunsmith to install them -- as it's complicated... I normally do stuff like that myself, but after following the Ghost instructions on their website, and examining everything, I chickened out.)