If you want to learn and you don't have a welder than I would suggest a TIG welder you can weld what ever you want. TIG will work for Alu., Steel, Stainless Steel just change your rod and in some cases your gas mix. I have a mig and have use my buddies TIG some what regular the TIG is is much nicer but will take longer to master but is so much more versatile. Spend your money there you'll be much HAPPIER.
Steve