I have found that it pays to buy good pedals, even if they cost quite a bit more than the cheap ones.

I bought cheap pedals for a spare bike once. Right out of the shop, a friend was riding and the pedal bent when he stood on it. He only weighed 165 pounds, although he was a very strong rider. The LBS offered to exchange them. I said no thanks. They did give me a nice discount on a better pair.