I used to use the camera store I managed, but they went out of business earlier this year. I found a local camera store nearby now and try and use them when I'm not printing on Caroline's Epson PictureMate. That is a pretty simple and easy to use home printer for 4x6's. We discovered an issue when trying to print our square Instagram images, but after a bit of work, she found a work around and we can do it now.
I have also used Walgreen's when they run print specials.