If she's going for box mixes I can understand the rationale: they're unbelievably cheap to produce and have a years-long shelf life, so spoilage won't be an issue.
Is the plan to sell them from her website? In general the baking mix market is one of speed and convenience: little Jonny needs to take cupcakes into school tomorrow for the charity drive but Mom's short on time, so she grabs a Sara Lee box mix. She obviously won't wait 3 weeks for a Meghan mix to be delivered. So maybe the USP will be the packaging and brand - corporate-style gifting.
Is Meghan hoping to have product on grocery store shelves? That'll east massively into her margins as manufacturers need to pay big $$$ to get premium space for their products in Whole Foods/Trader Joes etc etc. Martha Stewart has that market sewn up - a smaller brand won't be able to afford to take her shelf space.