My research tells me that hops is another one of those plants that "the experts" all say has to be propagated from rhizomes, because the seeds supposedly don't reliably come true. However this is something that's only sort of roughly true for many of the plants it is said about, and often it depends on just exactly what you are using the plants and their produce for. It's very much the case that the hops rhizomes I've seen for sale are very expensive, not practical for bulk plantings unless one is very rich.
Having said all that, the only place I've noticed hops seed for sale is
on eBay. I think I have some incoming as part of a larger order I made, because all I want is to grow some vines to shade a structure. I don't really care if I precisely reproduce one of the named brewing varieties.