You can get a miller or lincoln 120V wire feed welder for pretty cheap and you can weld up to about 3/16 with that using .030 flux core (.035 flux would be better).. Wire welding seems to be the normal starting point.
If you have 220V in the garage you can get a 220V wire feed but it'll cost ya more.
If you can swing it, get the miller 135 with a regulator. That way you can add gas to it later...
If you wanted to start with stick welding you can get a tombstone (big lincoln welder that looks like a tombstone) for pretty cheap. I've seen complete used setups (with mask, rods etc) for < $250.
Personally, just starting out, gmaw (wire feed, miller 135 etc) is cheap and easy to learn with.
~Mark