This is far from being an all-inclusive list. This nursery in Wales has gone out of their way to seek after some exceptionally cold hardy Eucalyptus provenances. They also sell live plants within Europe.
Seed is very expensive, but highly recommended.
A New Zealand company specializing in a wide range of cold-hardy Eucalyptus and other seed. They also sell plants within New Zealand. Bulk quantities of Tasmanian eucalypt and other seed, particularly some of the larger timber species used in forestry. Cold-hardy provenances available upon inquiry. Cold-hardy provenances available upon inquiry.