I would be very concerned about how secure the supply of coal is for the dealer to sell.
At this point it's not a problem if you have the cash to purchase all you need in the summer. If you can't do that you run the risk of a)not getting any b) paying a lot for it.
As mentioned above you need storage and a years supply will take up quite a bit. If you can't afford the outlay for the coal I'd suggest it wouldn't be a feasible adventure.Ideally you'd want to buy in bulk and bag yourself and/or sell in bulk. That would require additional capital for loader/certified scale/ etc. If you don't have a coal supply then I think it would be hard to sell the stoves.. besides the coal is where the money is at. You only sell someone a stove once, a few maybe a couple...
It's one of those things that if you have the cash it could pay off very well in the long run. That's one of the reasons I don't have too much worries about competition popping up out of the blue, the lift you need costs more than the truck.... Then you need to know how to operate it correctly, by that I mean use it so you don't kill yourself or anyone else. This isn't a job you can just let anyone do, they need to be trained and finding people willing to do this job that I would trust are few and far between.