Devil, I try to buy them when I see them on sale at Dick's, etc. Believe theres some you can find online, but I prefer the Spros.
Grass shrimp can be killer.
Used to have a few great flies that someone tied which hung as a teaser would always get bites.
Shrimp, crabs, small baitfish, etc...basically why I use as small of a bucktail that I can as it imitates a wide variety of small critters near the bottom.