You can build a bike with just an air mapp torch. Or even an air propane one, which is cleaner in my experience. But unless you enjoy the actual investigation in these techniques, you are better off getting a Tinman propane torch, and a propane cylinder, and an oxy cylinder.

best to get the SafetySilv off ebay if you can find it cheap. I got a 2 pound box at a rocking deal, but you can get an ounce also. Yeah, there are boutique offerings out there, but not for what you are proposing.