This one will be short, don't worry. It's about the website: http://www.bookdepository.com/, and my opinion about their service.
The first time I used this service, I did NOT have a great experience. Books arrived extremely late, although I will say that contacting them was a great idea as they were prompt with their responses and very helpful.
After a tentative break (because of this hassled first experience) I tried ordering from them again, and I would say that everything went smoothly. I got my books on time (within the 7-10 business days promised when shipping to Canada) and I've ordered from them numerous times since. I have had a GREAT experience ever since. The prices are much cheaper and the shipping could be questionable times (say 15 days to ship instead of 10; however, I would say given the great prices and free shipping it provides, it is still worth it.
I WOULD recommend using The Book Depository. Very good prices and FREE WORLDWIDE SHIPPING.