They stopped making it, and shipped out the leftover stock, projections state that in less than 10 years most film stock will vanish as it is not being manufactured anymore. Go digital (yes i know, polaroid has a really unique look.)

With that said, try ebay, www.henrys.com, www.adorama.com may have it.
Perhaps large department stores have some leftover (i just saw a stack of polaroid cameras for dirt cheap at wallmart less than a month ago, i'm sure they have the film somewhere in the store.)