Ebay isn't always cheaper

Today I went to look for some phonics books for my youngest daughter. I found them in the Early Learning Centre and was about to buy them when I thought that they might be cheaper on Ebay. When I got home and checked I found out that in fact not only were they dearer, they were more expensive by a few pounds. I wonder who buys things from Ebay that you can get cheaper in the shops. At least it taught me a lesson, that ebay isn't necessarily cheaper.