Not sure anymore. They were developed on Soft 3D, but I think Digimation took it over for the Max market. Not positive though.
However, you might just call Soft support and see if someone there knows a source. Perhaps your reseller might help.
How about posting on ebay, that you want to buy it. I'll bet there are plenty of artists willing to sell you their old copy. Maybe some other 3D sites that have buy/sell forums. This site did for a while, but pirates where frequenting too much.
Sorry I can't help.