The Suzuki DR650 seems to be a bargain on the 'Bay. Simon Morgan has been all over the place on his with no real problems (apart from trying to fight germans who spill his pint, but I digress).
Look for the model with the nose fairing (like the Dominator's).
Away from thumpers, the Honda CB500 or the Kwak ER5 are both superb commuters with very low running costs.
Or... to go another route, the Suzuki 400 Bergman (the carb model, not FI), is a brilliant bit of kit, comfortable, fast and keeps you dry. If you doubt this, ask Jethro, he had one on a short term loan.
GC