That's odd, thier online price is $6 per pound for coral rock. Maybe they charge more for individually selected pieces?
Tampa Bay Saltwater was the first company to get an aquaculture licence, so thier rock is the most mature aquacultured rock around. Aquacultured rock is more enviromentally friendly than wild gathered, and the stuff created in the US will have more life left on it than stuff that was shipped from overseas. TBS has really good facilities for gathering and holding rock.
I don't know if I'd pay $12 per pound for a tankfull, but maybe pick a few choice pieces from that pile and get the rest as thier "deco" or "base" rock.