Ours are made by Aixin Opto-electrical. I think if we can ever get past the language barrier we can get some decent parts out of them. It took two sets of samples before they realized we needed 3.3 volt receivers and not 5 volt!

You are right it is hard to find the parts on Google. I can't remember how we found them originally but it was some combination of part description and the Japanese standard for the connector, JIS C6500.

Thanks,
Stu