A Hobart 140 or 190 would be a good place to start. The 140 is a 115v machine, and I believe the 190 is 115v or 230v.
These are small wire feeder machines that can run either solid mig wire (with gas shielding) or flux-cored wire with or without gas shielding. I think these would lend to welding alot of different materials without too much start up expense.
Ideally a GTAW (Tig) machine with high frequency A/C and D/C would be the machine of choice, but it takes a little more skill and coordination to operate and is more expensive to get off the ground running.
There are a few combination machines out now that can stick weld, wire weld (Mig and flux-core), and also scratch start D/C Tig....all wrapped up in one machine. Miller, Hobart, ESAB, Lincoln and a few others that are name brand equipment that will take a beating and work everyday of the week with minimal maintenance.
Look around on the net and see what's in your price range and get busy welding stuff together.