I suppose it really comes down to your budget. For true live rock I would look at Tampa bay saltwater, probably the priciest option but it will come with all kinds of macro and micro fauna. "Live rock" typically found at a LFS is just cycled rock that has some bacteria built up on it. Then there is just plain old dry dead rock, IMO Bulk reef supply is a good option here. I personally would stay away from man made rock. Since I don't really know what all went into making it and could have some contaminants/ leaching issues.
There are pros and cons of each. True live rock you will get all kinds of life on it, the good and the bad. But it is usually a pretty quick cycle. Dry rock is a longer cycle to get the bacteria built up and some rock can have excess phosphate leach out of it.
I personally went with a majority of dry rock and if I remember right about 20-30 pounds of LFS rock to help move things along. My decision was based purely on cost. Good luck just my 2 cents.