I'm sure the D2:ED website will eventually link to various sites / stores that have the game for pre-order and/or order, at the appropriate time. The publisher may do this as well, and/or offer the game directly.

I used to check ebay.com separately from ebay.ca to find additional listings, but in the last couple years I think they have done a better job integrating sites. The last time I checked ebay.com was the end of last year, and the only extra listings that turned up were a couple that didn't ship to Canada. The listings from UK sellers generally show up after the main search result list, under ebay stores or international sellers, but I have not had any problems finding them from ebay.ca.

Anyway, for a new release ebay probably would not turn up the best deal (at least going by a couple new-ish games and movies I checked for awhile ago). Amazon may be a better bet, or the web sites for Best Buy / Future Shop / Staples (etc). If you have any local computer or game stores, they may be willing to special order the game, if they do not usually have much selection.