Well... I could see paying ~300 for a plant. But not a cattleya. Heck, you buy the $300 plant and some idiot releases 500 flasks of of mericlones, and you will be a very unhappy camper.
$300 for a paph or phrag (which can't be cloned, at least not usually) might be worth it. Or even more for a very select stud.
Although I'd like to announce that I could sell you some guaranteed unique awarded cattleyas for $5000... If anybody is interested.
I'd even let one of my nice equitant oncidiums go for that. If there is some sucker ... errr... customer... out there who really needs to drop that kind of cash, I'll be happy to oblige.