Most of the dahlia growers around the USA will ship pretty much anywhere you need them to. Just find the dahlias you want then go on the Colorado Dahlia Society site to the Big List & find out who has them for sale. You can also find a whole list of suppliers on that site & it will take you all winter to check them all out for cool new and/or unusual dahlias so by spring you will have what you need!

DECO,
I have had really high quality dahlias from http://www.lynchcreekdahlias.com/

I have gotten mine for the last 15 years from Swan Island in Oregon.

I use Ferncliff Gardens in British Columbia, Corralitos Gardens in CA, Dans Dahlias, and Connells Dahlias.
Do a google search for the web addresses.
DB