Eek well, i'm not exactly sure. I know that I once bought one for 350k, and once sold one for 400k. But this was a while back, (around 3 months ago) so don't trust me on this
Personally I'm not much of one for investing in heads. It's an easily renewable resource. BreezyMan or any other player can create as many heads as they want very quickly. If they go for 350k he could make over 2 million in the mater of minutes.
But there aren't too many going around in circulation. And note that I said this was around 3 months ago I'm not sure how much they go for these days