Regarding C. Margaret Hort - I would say that 60 bucks was a steal for a piece of this plant. l had to look it up, it was registered in 1962 and it is absolutely gorgeous. I would suspect this is one of those Heirloom Cattleyas which usually sell for several 100 Dollars.
If I were to use this particular Orchids in a breeding program, I would try to contact growers like Waldor Orchids. Waldor Orchids post sometimes old Cattleyas like that. Or simply search for Heirloom Cattleyas.
My question is - why persue an Orchid like that when there are dozens of just as gorgeous white Catts around for a lot less money.