You will find lr cheaper on line more often then at the lfs. But at the lfs you can hand pick your rock. Makes for a better look. Talk to your lfs see if they will cut you a deal if you buy 180-200lbs of rock. My lfs is 6.99 for 1-20lbs, 5.99 21-49lbs, 4.99 for over 50, but when i bought 200lbs they sold it for 3.99. Thats the same with online stores as well, becasue of shipping cost. The more you buy the more you will save. So the cheapest way will to be to all of it at once, no matter where you buy it from.