Here are some links on making your own LR, if you live in an apartment i'll tell you out of experience it's a pain in the a@@ to do. It's not hard to do just takes a lot of water changes to lower the ph when your curing the rock, before you even think of putting into your tank. It was kind of a fun project but in the end found someone getting out of the hobby and bought some real stuff for 2$ a pound.
http://www.geocities.com/CapeCanaver...ementRock.html
http://www.geocities.com/CapeCanaver...eLiveRock.html
http://www.geocities.com/CapeCanaver...rateRocks.html
http://www.reefs.org/library/talklog...an_110997.html
http://www.reefs.org/library/talklog...er_052498.html
http://www.athiel.com/lib3/arago.htm
And the big one.
http://www.garf.org/howtodoinformation.htm#Aragocrete
Have fun. 8)
Clinton