It'd be expensive to do plastic figures. You'd have to cut steel molds using these masters and those cost some serious cash. Not to mention the potential risk to the mold masters...
On the other hand, it'd be relatively safe -- and certainly less expensive -- to make silicone molds and then cast the figures in resin. Not that hard to do for someone who knows what he or she is doing. (If I could pull it off with those Alphabots and Alphanauts, anyone can do it!)
Still... Sometimes it's nice to leave the unproduced stuff as unproduced. There's something cool about toys that never happened. The "what if?" scenario that romantics and poets are so fond of.
It was sold privately a couple years ago -- I don't know who currently owns it, though it came out of the hands of a long-time prototype collector who I believe got it directly from Islyn Thomas -- founder of Thomas Toys (the two were friends). It was listed on eBay a few years ago for waaaaaay more than I could spend. It's one of my favorite pre-production pieces, something I'd love to own, and to this day I wish I'd found a way to scrape together the money. Oh well.