+1 on the all balls racing bearings, I find them quite good, and cheap too. If I remember right I did my quad front and back for well under $50.00.
That said, there isn't any reason why you couldn't take the old bearings to a bearing shop like BC bearing and get bearings from them, you might save a little bit of cash. But I like having the right bearings before I tear it apart, it makes my OCD flare up leaving projects in pieces all over my garage.