I didn't know there was one in Ash Grove. I've been to the one in Willard once this summer. It's pretty small. I guess it takes awhile for things like that to build up. I don't think they have a very good location.
I like the idea of buying things from Farmer's Markets. It's just a drop in a bucket if I buy a few plants at Walmart but I feel like I'm helping someone out a little if I buy plants at a Farmer's Market.

This one just had a few vendors, but I imagine they might grow as the season advances.

Different markets work in different ways. Sometimes vendors pay a one time fee to participate, other times they pay each time they set up. The rates vary quite a bit. Some markets require the vendors be there the entire time every open day of the market - this can be difficult because some vendors may only have summer produce. If you feel a market is small, or could be better, talk to the local vendors, find out how it is run. If it works against the vendors, there will be fewer choices. Get informed, then (as the buying public) contact those in charge and make sure they're doing what they need to encourage, not deter growth.