If you have a reef environment you can let the rock sit in and let life start growing on it for a few years you don't need to buy live rock.
You don't need all live rock for your tank. You can use dry rock for up to 80% of it and then spend money on the good stuff for the rest. I use Feller Stone's Antique Coral dry rock, 50# box runs about $100 from the LFS
. Then spend the money on the best live rock you can find. It may be worth it to just buy some aquacultured rock online. I had a customer get some for about $5/lb shipped and when he got it had live brain corals and sea fans on it.