After about the third time shopping around and getting quotes for $70-$80 PER WHEEL. So for every two sets of tires you buy, it's almost like you're paying for a third!
My investment in tire changing tools was about $100 or so. If you're going down the route of doing your own tires you have to make a choice. Everything comes down to two variables - Time and money. A nomar or similar machine will change tires pretty fast, but have a higher initial investment. Changing it with hand tools will be cheap, but require more time to do.
With a set of spoons it takes me about an hour a tire start to finish. Remove wheel, break the bead, unmount tire, mount new, seat the bead, inflate, balance. Not too bad, and I don't do it frequently enough to annoy me.
Balancing isn't a big deal, though I really took my time doing it the first time or two. My advice, get a GOOD balancer. Having a very straight bar and good bearings are very important. I don't have one (because I went cheaper and regret it), but Marc Parnes will come up frequently as quality if you research online.
http://www.marcparnes.com/Buyers_Guide.htm
If you have a good balancer, I promise you can balance a wheel. The concept is simple, find the heavy spot (it will rotate to the bottom) and then put wheel weights directly opposite to it. A little bit of trial and error to find the correct weight. When it's balanced, it won't rotate and settle to a heavy spot, because there won't be one (at least not a significant one).
Couple shots of my homemade stuff. The piece on the right normally lays flat on the ground so you can rest the rim on it (with a towel underneath) and not worry about the brake rotor or sprocket.