Amazon actually has pretty good prices on some Enid Blyton sets occasionally through third party sellers. I watch the sets and buy them when the price drops. I grew up reading Enid Blyton and the chapters in her books with the magical characters are perfect for bedtime reading. I also buy Enid Blyton books at book depository.
There's another series that my sons love and you can find it on amazon but it won't be published in the US till next year. It's the Sherlock Sam series. Good for more advanced readers but clean cut and good for younger children.