Yes.
Dudleyas are a bit of a special case (relative to many cacti and other plants that are extracted from nature for the black market) because they are not easy to grow outside their home climate. I mean, a few select species are, but the vast majority are not usually grown outside the Californias. I think this aspect actually drives wild plant extraction, because the harder and more unusual plants in any given succulent market are going to be the most valuable.
In any case, there are Dudleya producers in California, and if the people who did the exporting hooked up with them to export nursery produced plants, maybe that competing stream would reduce the flow of wild plants. Maybe the people who sack nature are too accustomed to the nearly costless acquisition they have discovered (costly to everyone else and to conservation of course) and wouldn't be willing to pay a fair price.
I would imagine the most effective solution for reasonable buyers would be to explain to them that their new wild-collected Dudleya has about a 99% chance of dying in its first year, especially if they try to grow it inside (as most probably do) or leave it outside on hot days in the rain. But who's going to say that, and who would really listen?
We got to see how conservation works first hand in parts of Puebla and Oaxaca when we traveled down there last year. They have a lot of amazing species (a wide diversity in a small area) and have to deal with people showing up to take plants. The way it works, you have to contract with a guide to go plant exploring.
The guide is local and knows where the cool plants are. They watch out for your safety and share their knowledge. They keep you from pulling out a shovel or yanking plants to put in your backpack. They know the people who live there and those people are always on the lookout for folks who do not belong. This system exists and functions as well as it does in large part due to the ecotourism (people like us coming to see amazing plants) that it makes possible.
It was really refreshing to see this system at work in a place where it really matters.
One of the plants that has been a huge target for poaching is Dudleya pachyphytum, which only exists in nature on part of an island off the coast of the Baja California peninsula. Cedros Island is essentially a wilderness because of the location. So there is no way anybody could conduct surveillance on who comes and goes. It turns out the most successful poachers actually contract with locals desperate for money. They travel in small boats to the location and claw these plants out of rock faces. The exporter never goes to the island, they just collect plants from the people who do.
The worst kind of poaching is organized at the wholesale level. It's not a single person showing up to take a little plant home (though I do not condone that either). It's people who show up and denude an entire area of the desired species, leaving nothing behind except what they couldn't reach or see. Someone did that to the native Dudleyas growing on the hill behind our house a couple of years ago. They were so sloppy about it that they dumped the scrappier plants they had collected before they left. Since I live here I was acutely aware of the before and after, and this was somebody going for everything. Except what would not generate $ for them.
