I'm keeping about 15-20 snails. Turbo, Margarita, Cerith, Bumble Bee, Nassarius, Banded Torch. About 3 of each. Also have about 15 small blue/red leg hermits. I'm also about to put 3 shrimp in the tank. A medium size cleaner shrimp and two small sexy shrimp. Even without the shrimp now my tank is working fine with the clean up crew i currently have. You'll figure out how much you need and when enough is enough when you start adding more into your tank. You just don't wont to overstock your tank. If you add to much of a clean up crew there might not be enough algee and other things in the tank for them to eat. You should be able to get the above for under $200. Your LFS should give you a break on the price if you buy everything from them at once. Try to create a good rep. with them. If you get in good with them they should be willing to help you out a lot more later on down the road. Good Luck