Keep watching eBay. "Poolm357" was selling 3 genuine Polaris scrubbers for $6 ($2 each) last fall, so I bought a good supply. The shipping was quite reasonable, if I remember correctly.

My local Leslie's used to sell a Pentair scrubber as a replacement but the foam did not hold up nearly as well as the Polaris brand. They've since returned to selling genuine Polaris but they are more expensive than eBay.