Come July 1st Ontario and B.C. will be introducing a harmonized Sales tax. Currently if I sell out of province and in Canada I only have to charge GST. But once the HST comes in I have to charge HST to all the provinces that employ HST. However, vendors in B.C. and Ontario can take payment in full by May1st for product that will be delivered after July 1st and not have to charge the provincial portion of the HST they just charge GST. This translates to a saving of 8% if you buy from Ontario and 7% From B.C..
If I ordered a kilt from Freedom Kilts in B.C. and I pay him before May 1st of this year and it takes him 8 weeks to deliver that kilt to me I just have to pay GST. If However I pay half now and half when the kilt is done the second half will be subject to HST. (The month of June is a gray area)
Those provinces that don't have HST will not be affected.

Out of country sales are not affected you save on both taxes but shipping is another issue.
Cheers
Robert