I have been looking online for hybrid standard cattleyas and better
species, especially semi-albas. I have found lots of pics to wet my
appetite but few sites with things for sale.

As an example of what I am looking for: you can find C. percivalliana
"Summit" FCC/AOS and C. percivalliana (no parents listed) everywhere.
I am looking for things like divisions or clones of C. percivalliana
"Sonia", or seedlings of C. percivalliana "Carache" x "Jewel". Not
necessarily those clones just something different with the potential
to be better than average.

Any help on finding vendors in the US?

Jim