Thanks to Kaili who mentioned on Facebook about the Book Depository company in UK. They have excellent prices on all kinds of books.
Incidentally my husband the University student came home one day and told me about this same book company. He found a few of his text books considerably cheaper than his on campus book store. Funny guy when he was in the Uni book store comparing prices, upon seeing that the Uni store was more expensive he said out loud rather loudly for all to hear 'I can't believe how expensive these books are!'
For example he saved $40 on a text book with The Book Depository, even with his discount as a member of the co-op at uni.