I'd frag that bad boy in a heart beat Unarce. As long as you're not the one running the price up, and that's what someone is freely offering you... take their money! I am always on the look out for a nice coral, but I think I top out at ~$150 for a frag. A whole colony is a different story.
I have to agree with Iron Chef, aussie Acanthastrea are the big craze right now. Micromussa is still hot but maybe on the downfall (sorry Doc, I hope Im wrong haahaa). Chalice corals (Echinophyllia, Oxypora, Mycedium) seem to be heating up as they should, quick growers, gorgeous colours, neat shapes.
Truth be told there are the untouchables that will always be a little more than everything else...and that's if you can find it in the first place.
I think people are actively looking for aussie acans, or anything Australian, the most right now.