My favorite place to buy plants for my gardens is from the Tualatin Valley Garden Club. They have a booth at my farmer's market every Saturday. The club is made up of people in the local area that love to garden. They are always willing to share their expertise. In addition to plants that I know grow well for my neighbors, I can buy yard art, planters, eggs, flowers and other in-season produce.
If you aren't lucky enough to have a garden club in your area, check for plant sales. Our city has a native plant sale at a local park one weekend in the spring, as does the Portland Japanese Garden, where I was able to buy some unusual perennials and bulbs. A local hotel chain that prides themselves on beautiful grounds also has a plant sale every Mother's Day. And I have also gotten plants from garage sales. So far, these plants tend to survive better than the nursery perennials that might not be suited for my climate.
I agree that my local grown plants seem to do better and we have a great Farmer's Market but it is only there on Saturdays so that kinda limits my visits (still a better day for most people) so I enlist help from neighbors who can go every Saturday. They buy me fresh vegetables and send me photos of any plants they think I might be interested in - nice to have "personal" shoppers!
I always try to remind people - Neighbors do not have to just be the ones who live next door - I try to be a good neighbor and hope they will be the same to me.
Happy planting!
Betty