Someone recently asked me where to find a "stewing hen." That's typically an old laying chicken that's at least three years old. That's a very specific type of chicken, and tougher than the type you'd find in a store. To find that type of chicken, find a local butcher and ask them to recommend farmers who might have some. You can also look on Craigslist or other sales sites.
This time of year, if you go to the local outdoor farmer's market, you can buy one and try it. If you're specifically looking for stewing hens, try asking the vendors with eggs. Even if they aren't selling processed chickens there, they probably have some at home.
For the best meat chicken on your table, typically a Cornish cross that's raised specifically for meat, build a relationship with the vendors at the farmer's market. Check on Craigslist and your local classified ads. This is also the way to find meat turkeys and waterfowl, although waterfowl are often harder to find. If you are having trouble finding waterfowl, ask your local butcher.
Most areas have county fairs with 4-H and FFA kids selling their poultry at Fur and Feather auctions. This is a great way to find high-quality birds. If you talk to the exhibitors after the sale, you can usually find someone who has more birds at home. This has the added benefit of supporting local youth.
Bottom line: it's easiest to find your source for a local chicken dinner during the summer, when there are many different sales venues. If you cultivate your relationships with them over the summer, you can be a regular buyer throughout the year.