Gravel from a fish store is going to be much more expensive then crushed stone from say... Home Depot, or a garden center. If the tank is somewhat small... say a less than 55 gallons I would use regular gravel from a fish store but if it is a larger tank greater than 55 gallons I would use crushed stones. Most 50 lbs bags of crushed small stone can be bought for 3.99 or less. 50lbs of aquarium gravel will cost you a small fortune in comparision.