The Guinea Fowl tang is an awesome fish. Only seen one at an LFS here in SA and it's in their display tank. It is reef safe and not as territorial as some of the other Zebrosoma family. Would kill to have one in my tank.
When I was living in Baltimore, one of the wholesalers in Washington, DC. got 7 of them in. He was selling them for $750 while still in the bag and $850 if he put them in his system. Anyone that has been to this place would tell you they would pay gladly $15000 instead for him not to put them in his system first. 2 of them came DOA and the other 5 sold within 2 days. The news of their arrival spread like wild fire. One guy I know that bought one said it died within a month.