I buy a lot of my daughter's shoes at Savers on Power and Baseline or Goodwill on Main and Recker. They seem to have better quality shoes, that haven't been worn a lot and are clean. It is kind of hit or miss, so don't get frustrated if you don't find something right away.
The other place I buy my kids shoes cheap is Ross. The one by Superstition Springs mall is NOT a great Ross, try the one on Power and Ray or the one on Stapley and Baseline. I can usually find name brand shoes for under $10 at Ross.
Those are my best suggestions, I am a cheapskate when it comes to shoes. I think it is ridiculous to charge over $30 for a pair of kids shoes!
Oh, one other idea, check out Ebay. It is harder to find shoes on there unless you are looking for specific shoes, like brand or color. However, sometimes you can find lots of shoes for under $10, just check the shipping first before you bid. And if you haven't checked out Craigslist, check that out as well. Just type in shoes and you will see how many are listed on there.