Before buying these on eBay why not check out the CGP website?

btw these guides are the best - I don't bother with any others. I used them myself for Maths GCSE and Level 3 and they are really useful for my children. Some bargains on eBay but sometimes it is better to go direct. Watch out for changing syllabus and also don't forget the Levels - there are different books for different levels at KS3 and GCSE.