http://www.treemendus-fruit.com/
This company, Tree Mendus fruit in Michigan, is incredible - they grow hundreds of varieties of heirloom apples (Ashmeads Kernel, Golden Russett, Esopus Spitzenberg, Kandil Sinap - you name it, they have it) - you can call them, ask them what is ripe, and they will send you what you want - one of this or one of that, a flat of what you want.
A few years ago, my wife and I sampled through dozens of heirloom apples. They are just really nice people over the phone as well...best to start calling early in the season (late Aug/early Sept) to see how their crops will be, what's doing well, what is coming in when, etc.
Tasting heirloom apples is as much fun as (gulp!!!...) tasting heirloom tomatoes!