All depend on how much money you want to tie up in all the changer and all the accessories that go with it. You will need an air compressor if you don't already have one.
What about balancing? Centramatics are about $230, tho that is a one-time shot. Dyna-Beads are about $10 and can be re-used if not lost in demounting. Otherwise you will need a balancing stand and adaptors.
And how much money you want to tie up depends on how much you are going to use it (how much do you ride and how often do you need new tires?) and storing it when not in use.
The least expensive is a large C clamp or other method to break the bead (there are many, just google for it) and about three long tire spoons, (16-18") with that and a old soda bottle (cut up for rim protectors) you can change your own tires. Throw in some beads or buy the balancing rings and you're done. If you have tender knees and don't like wrestling tires into submission on the floor, then as already mentioned above, you will want to buy a real changer.
I just bought 3 spoons off ebay for next to nothing. It was a set of 3 spoons.. They looked cheap but i said what the heck. I have a large c-clamp about 10 inches or so. I broke the bead and with the 3 spoons it took me about 15 minutes to remove and remount the new tire. It was a snap.
I do suggest 3 spoons. 2 just didnt give me enough to walk the spoons around the rim.