1) Depends, best On-board for gaming is VIA's ProSavage Video (Chipset KM133). I have one myself.
2) I would have to say, if you need On-board video ECS's K7VMA. It has KM133, and I chose it for my first DIY PC. It is stable, maybe lacking in OCing features, but still very good board and I got it for like $70.
3) First of all, no DDR board will have on-board video. Again, the cheapest DDR board that had something other than MAGiK was an ECS K7VTA3. Has, KT266 for $85. But I did see a AMD 760 board, FIC's AD11 for $109 and have heard great things about it.
All prices from Pricewatch.com