Wowcher always have good deals on photobooks.
I just got a nice one, a 100 page A4 hardback, for about £20 delivered (Huggler). 100 colour A4 prints at 20p each....I consider that a bargain as my 6x4 prints used to cost that back in 1980.
The B&W images aren't as contrasty as I'd hoped but that's the price you pay for cheap, automated, prints.
You tend to pay a lot more when there's a knowledgeable human looking at the images before printing, certainly more than £20. The colour images are surprisingly good reproductions though.