If you're starting out, you're looking for a pearl wholesale supplier, not a farmer. The pearls need to be processed (treated, sorted, drilled, matched, etc). Unless you have the ability to process the pearls yourself, the "hama-age," as it's called, isn't something you'll be able to work with.
There are a lot of wholesale dealers that advertise on Alibaba, but I'd recommend starting out in person. The lion share of pearl dealers in the US source from just a few pearl importing companies. Dealers visit them at trade shows in Tucson (coming up), Las Vegas and New York.
There are also international trade shows like the main Hong Kong gem show where you can meet pearl producers and processors from all over the world. As a dealer, you need to have economy of scale to source pearls in a meaningful way at these shows.