Here's the perspective from someone who is new to SW. I looked into SW almost 20 years ago, but stuck with FW because of stories of reefs being damaged by collectors using cyanide). More recently I got excited about reef aquariums, but then heard horror stories of reef damage caused by unscrupulous or indifferent collectors. Just a few weeks ago I saw something about dealers noticing that some live rock appears to have been sawed from reefs, rather than collected from rubble.
I decided to set up a reef tank only after seeing aquacultured corals offered in the Fosters & Smith catalog. I had no idea that corals were being aquacultured, and after doing a lot of research I found that a reef tank could be set up using methods that wouldn't damage existing reefs.
Although I made a reluctant decision to use some wild-collected LR instead of aquacultured LR (I plan to use 50% manufactured LR that I'm creating from cement and ground oyster shells), I would have purchased aquacultured LR if my LFS had offered it.
I will also seek out aquacultured corals when it comes time to stock the tank. I asked the LFS guy if they carried aquacultured corals, and we proceeded to have a long discussion about that. He said (and this is his opinion, I haven't verified this with anyone else) that a large amount of the corals offered for sale have been aquacultured, but distributors don't bother separating out or labeling aquacultured vs. wild-collected corals. His view of it was that his distributor moves such a large volume of product through their dist. center that they don't have the time or means to label individual specimens. Also, the distributor gets his stock from many different producers; some of them label individual specimens and some don't. And when they arrive at the LFS, even if a few specimens are labeled, the LFS doesn't bother keeping track of which are wild and which are aquacultured.
So, my take on all of this is there may be a demand out there for aquacultured corals, fish, etc. (or, in your case, for humanely harvested livestock), but the large-scale suppliers are focused on moving vast amounts of product as efficiently (meaning low-cost) as possible, which means they aren't going to focus on what may currently be just a niche market. I compare it organic produce. There has long been a market for small-scale producers and local retailers offering high-quality organic vegetables, but it took a long time for the Publix supermarkets and Wal-Mart supercenters to start stocking organics. And when they did, they were in small bins off to the side for twice the price. It took a company like Whole Foods to see the demand and to capitalize on it by building a business model around organic foods.
I agree with raaden: "The average consumer would probably not pay a premium, as most of them don't even know what humane captured livestock is or how it differs from anything else. " A big part of the effort may be to increase the demand by educating SW hobbyists -- let them know that you are offering them an alternative and tell them why they should choose your humanely-caught livestock over someone else's cheaper livestock. You only need a piece of the pie, not the entire pie.
Sorry for the long post, but the issue of "sustainable" (if you want to use an in-vogue buzzword) reef-keeping is a strong interest of mine. As I get deeper into reef-keeping and have more to show for it than a tank full of stinky rock, I hope to get more involved in aquaculture techniques and to promote methods that don't harm wild reefs.