Looking to buy used I would be looking at a Ram or GM 2008 to 2012 for your assumed price range.
If you choose a 2500/250 you will likely exceed the listed GVWR. That said if you are ok with running over GVWR then a 2500/250 is basically a 3500/350 just with slightly softer springs.
I tow a 12,360# GVWR with a 2001 Ram 2500 CTD 4X4, I am over the TV GVWR, but tows great. Would I rather be within GVWR, sure, but the current Ram runs great.
While I like the Cummins engine, I have no issues with the Dodge/Ram wrapper other than before 2013 their GVWR seemed low compared to what people carry and tow with it.