I've done a live chat with a cast member about this because I had the same plan for the kids Christmas gifts for our February trip. They don't sell/ship them to Canada, although she said she thought the Disney florist might. Not sure why they would and not have it be something you could do generally, but I haven't beeen in touch about that yet.
What I've decided to do, since I want to get some stocking stuffers anyway, is to go to the
Disney store in Mississauga and get a couple of blank cards to wrap up and give as gifts and will put something like "good for $x spending money at Disney". When we arrive at the resort, I'll get them actual loaded cards for their spending money.