The real irony is that the Yellow tang, Purple tang, Black tang , and Gem tang are all in the same family Zebrasoma. So you can spend anywhere from about $25 to $3,500 for fish that are essentially the same except for coloration.
I have a pintail, tonga flame, hawian flame, two mystery wrasses and a lineatus wrasse left.
I have seen black tangs for reasonable prices lately. If I hit the lottery I would have the gem tang, a conspic, two interruptus and a trip to hawaii to pick up two of everything Frank at RCT might have.