Depends on what you are planning on welding. If you are planning on welding light metals and assemblies of metal 1/4" and thinner, you could probably get by with one of the Millermatic 140, Hobart 140, or Lincoln 140 units for quite awhile. Get a 75/25 tank of gas to go with it.
The best thing about them is that they will not only work quite well, are easy to learn and adjust- but they are also portable since they are usually 110V machines. So, you can take it anywhere 110V power is available and go to work.
If you have an adult learning center or community college avaiable you should be able to take some welding classes in the evenings to help you get started.
Bob
