Model 8700. No camera, no WiFi. That's about the limit of your stated budget. If you spend a little more you can get a Curve 8320 and have WiFi access and a camera. If you wanted to go super cheap get an old 72xx model, but again, no camera or WiFi.
As for working with a generic smart phone plan, no Blackberry works well with them. A Blackberry Data Plan opens up a world of possibilities. It's not one model that works better than another, its the Operating System you load onto it. Anything that runs OS 4.5 will do a lot, but without a Blackberry data plan its hit-or-miss on what will work. If you go T-Mobile you can get a $30/month full BB data plan and run everything. It's only a $20/month add-on if you have a voice plan. That's about the cheapest deal in Blackberry data out there.
If you're not going to get a BB data plan, why get a BB? You might be better served with an unlocked Moto Q and T-Mobile's TZones at $5.99/month.