M.P.
I wouldn't do payless or walmart either. When i did ballet they slipped all over the place on my foot. I would highly suggest going to a dance store. My size at a women size 9 (I actually get 8 because you want a nice snug fit, but probably not for a 4 year old) and it was $18. $20 maybe with tax. I would go to a professional. As much as I LOVE thrift stores, shoes and especially dance shoes shouldn't be reused by other feet. They get molded to one foot, then they fit incorrectly on another foot.
***Mine were canvas. Sorry. Leather was maybe $5 more. Oh and here is a online dance store that I love
http://www.discountdance.com/dancewear/kids/ballet-slippe...
I saw a pair on here for girls leather for $13. Not bad at all!