I think Dan in Alaska makes a good point. Maybe look for shorter barrelled guns. The trick may be to find a heavy short barrelled O/U that isn't SO geared towards competition shooting that its got $1,000 of walnut on it.

Don't know about 3.5" shells. If you've been shooting 3" why do you want to change? Personally can't see the need for 3.5" shells in a 12gauge...any gauge for that matter but that's another topic for another thread. There are alot of "entry" O/U now like the Remington Premier, CZ makes one, Stoeger, Mossberg even makes one. (I handled a Mossberg at the Gander mountain and was amazed. For a $580 double its amazing...time will tell though).