Air pumps

Hi! I am a college student and I just started my first tank. Its a 27 gallon that I plan to keep shrimp and snails in, I am working on a second 10 gallon. I have some green rilli and blue dream neocardina but I am looking to keep more and some caridinas as well. If anyone is able to send me shrimp or tank supplies to MA that would be awesome! I am on a tight budget so the more I can buy second-hand the better. I am currently looking for air pumps, sponge filters, and a temperature adjustable heater. See less Marketplace has a lot of supplies cheap. Also I heard that most areas have aquarium auctions. I’ve never been to one but plan too.