I just noticed these while browsing the Bargain Cave site at www.cabelas.com and thought some fellow TFP'ers might benefit. I thought it a bit odd that they had a picture of a pool filter cartridge at a hunting and fishing store, but sure enough, it's the real deal. I don't have an above ground pool, but the price seems right for those that need to stock up for swim season. 
(Assuming that shipping costs don't kill the deal)
Link
(Assuming that shipping costs don't kill the deal)Link