You might want to check both Amazon and eBay if you are serious about getting an older version. How many models do you need to convert?
Shade3D has changed hands a few times. Shade 8 was an e-frontier version and was published in the USA by e-frontier America. Mirye handled Shade3D from versions 9 to 14. There was a Shade3D company that acquired Shade3D from e-frontier, and they started with 14.1.3, then sold it eventually to Forum8. Forum8 does have English speaking staff. Have you tried to contact them?