Amazon offer Prime members the Melissa & Doug Water Wow Alphabet Activity Book for $4.05 with free shipping. Plus, Prime members can opt for free no-rush shipping to bag a $1 Amazon Books or eBooks credit for every order placed. (There's a limit of one credit per order. Non-members can spend $35 to qualify for free shipping; otherwise, it adds $4.98.) Assuming you use the credit, that's the lowest total price we could find by $4. It features a refillable water pen that only marks the pages and disappears when dry.