And here are the replacements for 35USD from BikeNashbar:

And you can go to Niagara cycles for a huge selection of similar pedals.

Cheap metal platform pedals are not always better thanh the plastic ones (although they usually are). I had a pair of metal ones break on me once after a couple of years of light use.

Worse thing about plastic pedals is they're slippery in the wet. I almst came a cropper a couple of times with my plates of meat slipping off nearly followed by me. I swapped to metal platform pedals with a toe-clip. These work fine -- keep the ball of my foot in the right position and feet can't slip forward. Not as 'good' as clipless pedals but then I'm not a serious rider.