Also what is the most cost effective place to buy them? Making my own isn't really an option and at $5-10 each it seems like a big initial investment.
Oldest DD bought some from Naturally Cozy - she said they were expensive, but she only bought a couple to use as patterns to make her own. You might want to check it out.
She has purchased several kinds - one brand has an insert that fits into the part that snaps around the crotch of panties, effectively "doubling" the coverage for heavy flow days. She just soaks them in water, then Biz, before washing & it works fine for her.
They are pricey, but they last a long, long time. DD says they are a lot more comfortable, too.