Scott, I think your church can charge more, because Atlanta is a large cosmopolitan city, like Plantation, where people are used to higher fees. Here's a link to one that we have year around, put on by the city, and it always has at least 12 vendors. There is a link to the vendor application, which is 3 pages with rules and prices.
http://www.plantation.org/City-Gover...rs-market.html
Marsha