#3-gravel at pet shops can get pricey with small and large setups. being around $5 for 5lb bag.
so if you head over two your local lowes,home depot, walmart(haven't checked yet) and go to there sand, rock, and gravel isle and you will find that a 50lb sack of 1/2" and lower river rock is only $5!!! this is also a great place to get cheap sand for filters and substrate