This is where things can get pricey, depending on where you buy your hermit crab's enclosure. A glass tank is ALWAYS best. It holds humidity, escape-proof, available in a variety of different sizes to suit your crab-housing needs, and is relatively inexpensive. For 2-5 hermit crabs, a 10 gallon tank is ideal. You should think 2 gallons for every crab in the tank. You will also need a secure lid for the tank. A screen lid works best. You must have a lid to prevent escape. Next is substrate. Sand is the best. Gravel is an alternative, but I recommend sand. Hermit crabs will need something soft like that to burrow in when they molt. You can get sand by the bag at hardware stores. It's called play sand, and has been cleaned for use in sandboxes. There's also sand on the market called Calci-Sand. It was made specifically for animals that require sand, like reptiles, insects, and hermit crabs. It runs for approximately. $7 a bag and comes in assorted colors. Calci-Sand is full of calcium (hence the name) and will benefit your crab if eaten. If you're lucky enough to live near a beach, you can get sand for free. But you must rid it of bacteria, insects, etc. You can do this by baking it in the oven at 400 degrees for about an hour. However, this tends to stink up the house quite a bit, as I learned early in my crab-keeping career. You'd probably be better off buying sand. After you have the tank and the sand, you need to get the food and water dishes. A couple of clam shells work well, but you can also use jar lids. You've just completed the necessary set-up of your hermit crab's tank. Now for the fun part. Your hermit crab will need stuff to do in his tank, so why not buy him a few toys? By toys, I mean pieces of driftwood, textured rocks, coral, etc. You don't want to overcrowd the tank with these items, so only get a few. Wherever you get those things, you should boil them in water for about 10 minutes to rid them of bacteria, etc. Try propping up pieces of coral or driftwood on the sides of the tank for your hermit crab to climb. Have fun decorating your hermit crab's new home!