How much do vendors pay in order to have a booth?

$30 application fee, $15 per year GFM Association fee, and $15 per day parking for inside market. Further details are at this link: https://www.gastonfarmersmarket.org/becoming-a-vendor

Requirements are subject to change yearly. Please contact via phone and get info on their website. They have restrictions. You cannot just rent a space like a flea market.

Interesting question. The best way to get the information you want is to call them or stop by when they are open.