Thanks to Melissa McK for this Frugal Baby Tip!
I started off by using cheap washclothes from IKEA and Target (they were about 20 cents each) but the texture was a little harsh for my daughter's sensitive bum. I ended up buying 2 dozen of these: babysbottomline.com
They are a little pricey I suppose, but still cheaper than the wipes as we were spending about $17 a week in wipes before. So I think they are worth it. I also bought some flannel and microfleece from Joann's and plan to make my own but haven't gotten to it yet.
I just grab a few of the cloth wipes and wet them in warm water right before we start the diaper change. We keep a dish with a bar of Burt's Bee's soap near the changing table, just in case we need it, but usually the wipes with warm water are sufficient. We're still using disposable wipes on the go, becuase I haven't figured out a good system to use the cloth ones.