Buy a few pounds and seed dry rock. I don't like Florida rock personally. Its usually mined dry limerock maricultured which rarely have the shape options the good old fiji rock use to have. Primarily I don't like it because being local it's also too live with all types of pistol shrimp, mantis, macro algae and other creatures I don't want in my rock. The old shipped in wet newspaper, foul smelling, cure in a bin for weeks before use fiji rock mostly only had amphipods and bristle and beneficial hitchhikers eventually turn back up after the trauma of being shipped. I'd personally buy dry rock in the shapes/style I like and seed it with a few pieces of rock from an established set up before spending that kind of money on limerock dumped in the ocean and sold.
DOesn't seem that outrageous if air freight is included. I recently got a 100 lbs from GulfLiveRock.com and with air freight it was ~ $600. Keep in mind you don't need to use a lot. I only use about 1/4 to 1/2 lb live rock per gallon and usually about the same amount of local dry limestone. I wouldn't set up a system without it though. There's a lot of beneficial stuff on maricultured live rock you can't get any other way and if you QT it like everything else that lets you get rid of any pests. (By far most of the pests I've gotten have come from other aquarists which is why I QT everything from tanks I don't have a history with.) See AquaBiomics article on cycling with maricultured live rock and how it reduces the nuisance algae that shows up when bacteria cultures and culture live rock did not.