Does anyone know of anywhere that sell small compressed air tanks? I prefer it to be around 30-40oz size. I want it to dust the inside of my PC and desk area. I have a compressor in the garage but it's too big to lug around the computer room. I've seen small tanks for paintball guns, but I don't think those you can refill with a compressor. Does any store sell small tanks? I don't need it to be high psi, since it's just for dusting.