My best suggestion here would be to follow Ren's example from FoolCraft - Find a supply of the blocks/items you can't get any other way, and sell those. Whether it's blocks that only spawn in the world, or blocks with materials that are really hard to come by that you have access to a farm for, such a thing would sell fairly well when you let people know that you have those items (as you could do here, maybe even updating the first post with the list?) in stock.
That being said, I've always been a fan of the quartz blocks (Chiseled and Fancy), and too few people sell quartz. A solid source of just basic Quartz Blocks (the four Nether Quartz in a 2x2 pattern) would be an instant hit with me, and anyone else who likes building with said quartz blocks.
Archive
