Hoya sp. GPS 7240 carries Gerard Paul Shirley’s accession number. He is a renown collector and runs an internet based sales catalog based in the Netherlands. Here is a recent video that I found of his operation:

It is unfortunate that he won’t sell to, or ship to the U.S. as I guess many years ago he got burned, and has never wanted to ship here again. He will however ship to Canada and most of the rest of the world.