Tubers and plants are available in many ways.
1. Check out local society sales and auctions.
2. There are now many online suppliers.
3. ADS does not maintain supplier information, but provide the following links for your convenience.
http://www.dahliafarmassociation.com/
https://coloradodahlias.net/index.php/suppliers/
4. Many “big box” stores, garden stores and nurseries, and garden catalogs sell tubers and/or plants.