The ones on tradeex are good utility grade guns. I'm not sure if they all have the 2 1/2" chambers. If so, it is going to cost you more for shells and selection in this country of 2 1/2" is very limited. Unless you reload yourself and cut down the hulls.
Another thing to consider. By the sounds of it you already have a SxS or two as you stated you want to add to your collection. Take it from somewho who knows, save your money and look for SxS's that are more desireable to the collectable standpoint. If you want a decent collection of SxS's, there's no point of having a bunch of dime-a-dozen SxS's that aren't that appealing. Now if you just want a shooter to knock around and don't care about, that's another thing. This of course is just my opinion but if a guy is "collecting", then at some point one has to become selective with what they collect.