I know that some objects and custom food can't be sold. It's not so much as they can't be placed in Decra-Chills or OFB shelves, it's just that they can't be marked for sale even if they are placeable in shelves. I don't plan on using OFB shelves as I have my own, I just need to be able to sell the objects/food. Is there a way to change their object data in SimPE to be set for sale or do I need something like Numenor's custom objects placeable on OFB displays and shelves mod?

There is most definitely a way, and I think I've seen a tutorial somewhere, but I'm afraid I have no idea where. I'm sure someone will know one though