I commonly get requests for scion wood or questions about where to find scions in general, or of a particular variety. Below are my best recommendations.
Scion Exchanges and Swaps
These are usually free, sometimes with a small entrance fee, but I've never heard of one where the scions are not free. There are more and more of them, though large areas of the U.S. still don't have any. Search the web for terms like scion exchange, scion swap, grafting class or grafting workshop along with your large city, state or region. If there are none nearby, maybe you can find some like minded people and eventually start one. To my way of thinking, there should be one within easy driving distance of everywhere :)
Online Trading, Fruit Communities and Fruit and Nut Organizations
Below are listed some online forums, destinations and organizations where people trade cuttings and seeds. They generally are also places to meet like minded people in your region. The best information and collaborations are often local.
NORTH AMERICAN SCION EXCHANGE Facebook page: https://www.facebook.com/groups/scion... Started by my Friends Andy and Little John because they had no nearby scion exchanges. There is a website too, but the facebook group is most active
Home Orchard Society (Pacific Northwest): http://www.homeorchardsociety.org/ An excellent organization for NorthWesterners. From what I hear, their scion swap is one of the largest and best in the country.
Temperate Orchard Society: Apparently cloned the enormous Nick Botner apple collection, so they should have over 2000 apple varieties. (scion sales) http://www.temperateorchardconservancy.org/contact-us/
SEEDS Durham North Carolina: http://www.seedsnc.org/2018/01/upcoming-grafting-workshop-scion-exchange/
Michigan Home Orchard group: https://groups.google.com/forum/#!forum/mi-home-orchard Group by YouTube user Prof Kent for michigan folks.
Finally, you can buy scions. They have become more expensive, but if you really want a variety and you can't find it anywhere else, it might be worthwhile. Also, once you get interesting varieties, it gives you trading leverage. I sell scions sometimes, but I rarely trade, because I'm not collecting much anymore. Also, the apples that remain on my wants list are very rare, some probably even extinct or at least lost. If you want a specific variety, just search the net for the variety name and the work scion. You might be surprised to find some for sale, or to find at least someone that grows that variety or has it for trade. If I have scions for trade, they will be in the webstore around January and February. Unless you have some amazing rare stuff to trade, don't contact me about trading. I like to help people and will go out of my way to help serious collectors and breeders, but I get way too many requests. If you can find it anywhere else, please do.
If were to make a list of scion wood sources, they would all be on this page on the GrowingFruit.org site anyway, so I'll just refer you there.... http://growingfruit.org/t/scionwood-sources/3346
Grafting, the collecting fruit varieties and scion trading are fast growing in popularity, and for good reason. It's always an adventure finding out about new varieties, tracking them down and fruiting them out. I hope it grows enormously in the future. It is important to the preservation of food plant diversity that everyday citizens grow, share, eat, talk about and even create many different varieties. Even at it's most diverse, the larger industrial food model will always lack true diversity and soul. When there are quite possibly tens of thousands of apple varieties, even 20 varieties in markets looks pretty weak.
Feel free to contact me or leave a comment if you know of other good online communities, organizations or annual scion exchanges. Happy hunting