I have a friend who did this for a while. She had a trailer she took from show to show and had quite a bit of stuff for sale (mainly show clothes). She had a very nice display but I'm not sure it was exactly "profitable". I personally thought she was over charging for things as you could generally get the same items on ebay
for a little less. Plus, she was selling mainly higher end stuff (tailored sportsmans, custom hunt coats, etc) at mainly schooling shows. It was a good idea because it did give people who are leary of ebay a place to get nicer things at a cheaper price, but you do need to know your audience! Bringing a trailer to shows was a fantastic idea because she didn't really have enough to open up a "store" but it allowed her to bring what she had to a group of horse people. And she only had to pay the show a "vendor fee", instead of paying for a space for a store. You could also organize a semi-annual "garage sale" type event for a bunch of barns in the area. Have everyone bring you what they want to get rid of, they get a certain amount, and you get a percentage of the commission for what sells. What's leftover (and unwanted) could get donated to a local horse therapy place. I do quite a bit of selling on ebay and people or often asking me if I'll sell things for them. My advice is 1) know what price things are going for (so you aren't asking too much or too little) and 2) only take in what's going to sell! I have a pair of size 9 cheap rubber boots. Believe me, no one wants these! It'll be like, $15 to ship them somewhere and i'll make, what, a dollar? Not really worth the gas to the post office to ship them!