I know this has come up many times in the past so when I stumbled upon PoziDrive driver bits today in the HomeDepot I thought I would pass on the tip (Pardon the pun please).
There are two driver bit sets, a 29 piece, and a 30 piece, both are three dollars apiece. Between the two there are bits sized from PZ0 to PZ3, with some duplication. I thought that $6 wasn't a bad price to have all these in the tool box.
They are in private labeled assortments sold under the HD brand.
Bob
bownes