1 gal tank

Anyone have a 1gal tank that mounts to top of frame? Would like to get a little more range out of the bike. If not, anyone know where I can buy one? I found a place online that sells them in a kit, but they didn't answer me when I asked if I could buy just the tank, and I've lost the address. Thanks.
That's not a bad idea, I was thinking about getting an aluminum fuel bottle, but I figured, why not just upgrade the tank and not worry about it. I'll look for motorcycle tanks. Maybe off a Rebel or something. Thanks again.