I bought a few cheap ones plus Pediped ones as part of a spree so ended up paying around SGD20-30 per pair of the Pedipeds (including shipping).
I found that with the cheap sandals, Eva's right toes would stick out and rub against the floor each time she walked - a sign that the shoe is ill-fitting. Also, I would have problems putting on the cheaper shoes because the top is too small and I have to squeezer her foot in (but if I get one size bigger, the area around the heel would slip out). Fitting- and quality-wise, basically, I got what I paid for.
Even though Eva's on the small side, the Pediped shoes fit her well. The sole is sturdy yet flexible and comfy. The others I bought are flexible but thinner than the Pediped and dont't seem to have much cushion feel to it. Even my hubby who is a shoe snob agreed that it was a good investment. I'm one of those mummies who prefer to spend money on one good quality pair of shoes than a few cheap ones. I dont't buy any of the "cheap" ones I bought these days because the price I pay for the Pediped and cheap ones are nearly the same!