Seems like your hobby is taking a knife and making it more expensive for other people while adding nothing of value to it yourself.
That's not much of a hobby- that's lazy, opportunistic profiteering.
I know people who make money on their hobbies, too. They get a store front and then they buy all these hobby-related items at a low cost, and then they open the doors and people come in to browse and purchase these items at a higher cost. They mark up the items a few bucks so they can turn a profit. You're running a business. "but it's not my fault they didn't ask for more, and it's not my fault people pay my prices". cut it out- it's totally your fault because you saw a situation you could inject yourself into and make it work for your benefit.
I'm strongly in favor of a flipper list and a flipper tax, and I'd put you right up in the first slot.