In all seriousness, you could grow and sell probiotic cultures. There are a bunch of them that are hard to get your hands on, at least as a consumer in a reasonable form factor for a sane price. It's all the rage now, and for good reason.
And before you say this needs $100k in equipment, bear in mind that there are motherfuckers out there on youtube etching microchips in their garage using machines they cobbled together from junk. Be creative and figure out how to do it on a budget.