NOTICE: I no longer have time to add items to this site. I encourage you to keep contributing; however I'm not sure if/when I'll be able to get to them. I also encourage you to be active and contribute on our Facebook Page.
There was one recently listed on ebay that sold for $1800. Here are some of the things lsited in the description about it:
I MET JIM IN 1975 WHEN HE SOLD ME THIS PLANTER WHICH, IF MEMORY SERVES ME CORRECTLY, HE SAID WAS A TEST PIECE. I ALSO BOUGHT A MUG WHICH I LATER GAVE TO FORREST J ACKERMAN AND PROBABLY WAS AUCTIONED OFF DURING HIS ESTATE SALE. THIS HORNED DEMON SKULL IS DATED 1973 AND SIGNED. ONLY ONE OTHER HAS BEEN SEEN AND OFFERED IN 2003. AT THE TIME IT WAS THOUGHT TO BE ONE OF A KIND. I DIDN'T KNOW ANYONE WAS LOOKING FOR ANOTHER. I THINK JIM SAID HE ONLY MADE THE TWO, BUT I'M NOT SURE. I'VE HAD THIS SKULL ON MY BOOKCASE (COULDN'T BEAR TO PUT A PLANT IN IT) ALL THESE YEARS. IT'S MINT. NO CRACKS, NO DAMAGE. AN EXTREMELY RARE ITEM BY A VERY TALENTED ARTIST WHO HAS LEFT US ALL TOO SOON. I MET HIM ONLY BRIEFLY BUT STILL REMEMBER HIS GREAT SENSE OF HUMOR AND ENTHUSIASM FOR ALL THINGS FANTASTICAL. Added by THE RUMPH Webmaster from Dallas, TX on 10/13/2013