I'm like you, I've never welded anything before. I found a used MIG welder for pretty cheap. If you can wait for a good deal to come along, it eventually will. Just today I saw a MIG/TIG Lincoln welder that was only used twice. Asking price was $300 for a welder that usually sells closer to $550.
I like my welder. Its a Clarke 130 MIG and uses 115 household current. I do not plan to do any frame welding because I am new at welding AND my truck frame is solid and won't need it.
Folks on here like the Hobart 140, Miller and Lincoln models a lot. I'd stay away from the welders from Harbor Freight mostly because they are not gonna be as versatile.
Let us know what you finally get.