I went ahead and bought Beauty and the Beast 3D region free blu ray (2017) for $8.65 on Ebay. Of course, the next day, they dropped the price to $8.22. It will take a few weeks to get here since it is coming from England. This is actually less money than it would cost me to rent this same movie (in 3D).
There are a couple of stores on Ebay, mediamerchuk, which runs a site called
hawkeyeretail, and rarewaves, that both sell 3d blu rays from England at low prices. Some are region free and some are region B, and sometimes the region designation in the descriptions can be vague, particularly at rarewaves. I think rarewaves doesn't accept Paypal payments anymore, which is off-putting for me.
I've bought 3d blu rays from both stores before. So far, so good.
Some current 3D blu ray titles (new) from these stores, Ghostbusters and Goosebumps, $6.14 each. Monster's University, $6.69, Big Hero 6, $8.24 (I paid $9 for a used disk of this last year). Looks like they've got about 20 Disney 3D movies under $10.