Depending on what type of farmer's market you are looking for and how far outside of the city you want to go here are a few:
1. Chestnut Hill Farmer's Market (still in city) - 8229 Germantown Ave. 215-254-4900
2. Lancaster County Farmer's Market - 389 West Lancaster Ave 610-6878432 lancastercountyfarmersmarket.com
3. Flourtown Farmer's Market 1520 Bethlehem Pike, Flourtown
Then, of course, you have all the wonderful markets in out in Lancaster, Pa - Central Market, Bird-in-Hand, etc.
Would be remiss in mentioning the Ardmore Farmer's Market! Great location and great stalls inside; not to mention clean and bright inside. Prices might be a tad higher than at the supermarket or other specialty stores, but everything is fresh and high quality!
The convenience of having so many different stalls in one location is worth every cent (fish, meat, cheese, and pastries)!
I generally find the Chestnut Hill market has far more meat and seafood than produce. Not that there's anything wrong with that.
However, I was there about a month ago and made a startling discovery--some really excellent gelato, very creamy. The owner was very nice too--let my friends and I try all we wanted before we settled on our flavors. I had an excellent mocha with thin wafers of dark chocolate embedded. It was delicious. Forget was the others had as I was too intent on mine.
Is there any year round farmers market in Philadelphia other than the Fair Food stand in RTM? The only place I know of is a bit of a drive - Highland Orchards in Wilmington, DE. They sell their own produce, jarred/canned goods, plus local cheese, yogurts, meats, grains, and a bit of out of region produce.