unfortunately, keeping large amounts of shrimp can be an ordeal in itself. I have a designated 10 gallon tank setup to hold shrimps..I also keep some in a breedernet in my refuge of my larger setup, since a 10 gallon can only probably hold 100 until its too much bio-load.
Since you live in san diego, are you near the shore? It may take time to find an appriopriate spot, but areas with a lot of rock and not really a sand beach, you may be able to find shore crabs that live under rocks. I live in san francisco and find these here. Saves a LOT of money..Well I guess I have 15 more mouths to feed.. You can keep these in a 5 gallon bucket with some water and rock...