So this was interesting. I went to take a look at the web site and picked four books I was interested in. However, before clicking buy, I always check on Inkmesh to make sure I'm getting the best price possible.
One of the books they specifically mention as being a good deal, the Ware Tetralogy by Rudy Rucker (sounded interesting and for five pounds, I thought why not) turned out to be free from Feedbooks and Many Books. The other three I'm interested in are cheaper (well, two are much cheaper and one is virtually the same price, though it's not on sale) but the moral of the story: make sure you double check before assuming a "sale" really is a great deal.
Still, thanks. I think I'm going to buy the other three books (hemming and hawing about the one that's not on sale actually. I may hold off on that).