I live in Canada and have had great experiences with Vistaprint for wedding related, and non-wedding related items. We recently ordered 100 STD postcards, envelopes, magnets, and a return address stamp for the cost of $35 including shipping. It would have cost less except that my fiance felt guilty for getting everything for free, so we upped the number of magnets and postcards from the amount we would've gotten for free! We ended up using them all anyway because more and more people kept expressing interest in coming to our wedding!
The only issue that I've had (which isn't their fault) is that if you select the cheapest form of shipping, it does take a few weeks to arrive. However, you could always pay the extra for express shipping!