With that weight you will run into problems with most road bikes as their tubes are thin and you will bottom out the wheels. Don't get a piece of **** walmart bike. I'd go on craigslists and get a hairtail steel mountain bike with a cromo fork (no shocks, your weight will make shocks kinda stupid, especially if you're riding road they are pointless anyway). Then get some slicks for it.
I would suggest a specialized or trek cromoly bike. I ride road and cyclocross myself so I don't know mountain models well, but I think a Specialized hardrock or rockhopper from the late 90's would prolly cost about 150 in decent shape and do you well. Also check your local bike shop.
