I've read all the replies and it's been fascinating. So far, I've only sold live chickens & cow/calf pairs, so I'm no pork expert, but to me it seems you need to plan for the end in the beginning.
By that I mean finding your customers and their price points first before going in whole hog, so to speak. There may not be a big enough market for you to make money. I know a farmer who sold his pork shoulder for $8/pound at the farmer's market. You can find bone-in pork shoulder at the the local market "on sale" for $0.99/pound. Clearly, he needs an outside job to support himself! :-) (I'm one of the small number of customers he has for boneless pork chops, pork shoulder, as well as buying $5/dozen eggs)
I guess I don't understand the nitch your trying to fill. You think there is a demand for heritage piglets? If you're selling to a grower that might work, but they need to buy your piglet, raise them over the winter and market them themselves so your unlikely to extract the highest price from them. If your selling to another homesteader that might work but they will likely only buy 1-3 piglets for self-consumption unless THEY are trying to get a retail market going. In that case you need 4 to 11 homesteaders that want a fall piglet. It most definitely sounds like a feast or famine business model that would need a lot of research and prep-work.
Since you've got the hogs and piglets already it's a little late to worry about what you could have done. I guess I would spend all my time actively recruiting homesteaders to raise a hog or two for home consumption. That would include both information on why heritage breeds are best, where to have them butchered, how to build a cheap shelter, how to feed them, etc. I saw a YouTube video by some lady on building a 16' x 16' temporary hog confinement for two pigs for a homestead just using four hog fences and a couple posts. What she liked was that after they grew she could take the setup down rather than have a permenant structure. It's not very animal friendly but it could work.
If you build your own customer base, and they grow to enjoy the taste of home grown hogs or the experience of growing them themselves you could have a regular winter heritage piglet sale...or not. >;-) Good luck!