That won't work. Unless you are soldering very small parts like electronic connections, and even then... I made a rack using a MAPP torch, and that worked to a certain extent. OA torch is @ 6500 degree F. That is required to transfer heat quickly to larger parts. More gradual heating also works with a LARGE flame. To use the MAPP torch to do larger parts like tubes is iffy, has been done, tends to be at the ragged edge of what can be acheived while getting proper adhesion and not burning impurities. The point is that you heat the part, and the part heats the brazing rod, just melting the "solder" will not get it to penetrate the expanded pores on the surface of the part.
There are a number of things that can be done on the cheap. The problem is that most of them are attempted by newbies on a budget, narturally, and they tend to involve advanced skills. Another example would be stick welding bike frames, maybe even with a cheapo AC unit. No problem but harder than welding with the "right" rig.