Thanks for all the great advice. I have bought the walking foot and open toe foot already, and I think I'm covered. I do intend to learn to sew more clothes.
It's good to know the Brother feet are interchangeable, since I have a Brother too. Thanks for the link to the site with free shipping, and great return policy.
The store I was looking at on eBay does sell genuine feet at a great price, so I respect your advice and will wait to see if I actually need something before I buy it. I think I got caught up in Hubby's fever -- he's a mechanic and has every tool under the sun, and is always encouraging me to buy more "tools".