Perhaps you could learn to make them and sell them yourself! Modeled after your own.
I haven't seen any as nice looking as yours is. The ones I've seen here are flimsy and cheap looking... and/or bright colors that shock my sensibilities. They should be black or brown, and not electric blue or green.
I did see a leather combo for sale here, but it was very expensive. I think there's a market for a good quality nylon one.
I like a 12ft long, 3/4" thick nylon yacht cord lead with heavy twist-lock brass snap on one end and an 8" latego popper on the other and buying them from one of the popular trainer's website is incredibly expensive. I thought "I can make one for a whole lot less than that", so I decided to try. Learning how to splice the rope was the hard part, but once you get the hang of it, it's not that difficult. I get a little better at it each time I make one. I haven't sold any yet, just made them and given them away to my riding buddies so far, but one of my friends friends wants one so I might sell one to her if I have enough rope left.