I haven't sold climbing gear, but worked part time as an instructor at a dive shop for ten years and learned something about the sporting gear sales business (I did it for fun, and to get pro deals on gear, but it wouldn't have supported me in SF without a day job).
Although few retailers make much money in that business, the guy who owned the shop I worked for was pretty successful. One of his secrets was that he bought the rights to several well-known scuba equipment brand names, and then manufactured inexpensive (and low quality) gear overseas which he sold under those brands at his shop, and eventually at many other shops. He specifically targetted items which every student is required to buy to take a dive class, and which you can't rent (masks, fins, snorkel), but eventually branched out into other gear areas, as long as they didn't require a lot of engineering R&D. His manufacturing costs were very low and so his brands were always the low priced choice. His thinking was that a large percentage of people who take dive classes go diving once or twice on tropical vacations, and never dive again, so won't care that their gear is poorly made and falls apart. On the other hand, most people are very sensitive to price, and if they're new to the sport don't know the difference between good gear and crap, so will often buy whatever is cheapest, especially if the shop staff use that gear when teaching. The instructional staff were required to use that gear when teaching, but since we got it free or very, very cheap, and could write off any cost on taxes, most didn't care if it was POS. Instructional dives are never cutting edge, and we were free to use better quality brands, which we also got at cost, for our own serious dives.
If you can find a cheap crap niche in the mountaineering gear business, I'm sure there's lots of money to be made.