I and some friends bought for some thousands USD hard cash of plants and flasks of Bear x ro blabla, etc... and they turned out to be terrible, not from the supposed parents. For roth and sanderianum, it is better to target the more expensive nurseries, or individual seedlings. So far exceedingly few rothschildianum sibs from Taiwan turned out to be good, except small batches here and there, and most were absolutely not from the supposed parents.I haven't found anyone with roth or sanderianum flasks in the states, thats why I'm looking to import. If they were being offered here, I would buy here.
Try to contact Iweyshen/Shen Yi Wei. I got plants from him, and the quality was fine to excellent, but for sure he did not cheat on the parentage.
I got seedlings of several of his roths crosses, all bloomed looking like one or the other parents, some really good ones. The HS plants, I got them, several friends got them ( some Taiwanese even got them), and we did not bloom a single plant that looked remotely close to any of his parents.