Confirmed retailers
Use the drop-down box for your country of choice:
https://www.guildwars2.com/en/retailers/#UnitedStates-physical
Good luck.
For some reason Canada isn’t in the retail list. How odd.
I have unpleasant news for you. The box only contains the serial code. You still have to download the content. (Although if you are playing now, you have already downloaded a lot of it.)
Unlike the pre-purchase edition, the standard edition will not be restricted to specific retailers. Although it’ll likely be rare, you should be able to find it just like you would any other game. Gamestop or Amazon will be your likely choices.
Assuming the standard edition even comes with a disc, I wouldn’t count on it preventing you from having to download it. HoT is the base game now, so the disc will likely be wasted on the that. Assuming you’re playing GW2 now, HoT will likely only be a ~10 GB patch.
The launcher does resume where it left off. Some people confuse it as restarting completely since the progress starts from 0%, but that progress is based on the number of files remaining to download. You can also rely on the streaming option to begin playing HoT while the rest of it downloads.