I'd advertise out in the classifieds here and in that other forum; there must be folks out there who have damaged/cracked/destroyed a head, and have the other perfectly good one sitting around wondering what to do with it. I'd advertise "Wanted - one Trick Flow Head" with the part number you're looking for. Something should turn up. I've also found that on ebay, when I find a seller that has a pair of something I'm looking for, I'll email them and ask if they know of a source that has just one for sale. That often provides other contacts.