Paul,
The trouble with purchasing any welding equipment is that the cost of the power source, while significant, is not the only cost involved. You can almost spend $400 on one of the new autodarking hoods. But for your purposes, I think one of the 110v AC stick (SMAW) machines will fit your needs. You can plug it into any circuit that has a breaker to carry the load. You need understand that AC usually does not penetrate as much as DC+and usually more than DC- for stick welds. I would hit a few garage sales and maybe some auctions, or the classifieds in the newspaper. That way you can get the welding leads along with the machine. But you know the list starts getting endless when you talk about all of the tools you need to weld. Wire brush, chipping hammer, grinder, cutting torch, clamps, gloves, welding hood, etc.
I would check around your neighborhood and I am sure you can find someone who has welding equipment. You can learn alot just watching someone who knows what he (she/w3tcompact/icons/smile.gif) is doing. If your not too pushy most people would be flattered to show you what you want to learn at no cost/w3tcompact/icons/shocked.gif to you. Hang out at some of the welding supply places and ask a few questions, you know you are going to have to buy welding electrodes anyway. Speaking of which I like a E6013 electrode as it looks pretty good but it is not real deep penetrating rod. Get a E6011 for deep penetrating and the diameter is very important. It will depend upon the capacity of the welding machine you have, how thick a piece you are welding on and how much weld metal you want to put down. Usually 1/8" or maybe 3/32" should be fine for your needs. Hope this gives you some ideas.
Randy