Chocolate ...
especially batons for croissants because they can be hard to find locally.
Sachertorte from the source. (Okay, only once so far for our anniversary, but I'd do it again.)
Spices are tricky, because I like to see them first, to make sure I'm not buying a bag of twigs and dust.
Bulk buying of canned goods, other heavy things, big jugs of water in case of emergencies, because we don't drive.