Breeding is something that takes a lot of time and insight and experimentation. Speaking as a total amateur, I admire the people who dedicate themselves to the long road. The prices on some of these plants may be obscene but they do reflect some sort of recognition in the marketplace for rarity and exclusivity. As does the interest by thieves.
It's actually really hard to get anything good out of irradiating plants (or pick your poison, with the same desired effect). This I can say having spent some years making mutants on purpose to study things. Mother nature generates a pretty good amount of variation on her own (to be exploited by breeding). Your average induced mutant is either dead or seriously defective, very very rarely is it different in a way you care about. You'd have to grow more than a million plants to have a hope of seeing something specific. And more than likely also backcross any trait which might arise. Kind of a hard way to go, not practical in reality.
The genetic manipulation that takes place on the largest scale (beyond breeding, of course) is when they put in genes for certain things. For example the Roundup ready products by Monsanto which are resistant to a herbicide, allowing for the whole field to be sprayed without killing the crops. Of course when you do this and select on a massive scale (zillions of plants), you will find those genes can travel to weedy plants and render the whole scheme ineffective, and that is the real-world result with those products. It was always an I-told-you-so sort of situation, just a matter of when. Anyway, none of this has been applied to succulents.
