If your kids are anything like mine, they absolutely love to get mail. Everyday my dd looks forward to getting the mail and seeing if there is anything for her (I usually just give her my junk mail and that seems to keep her content!).
Last year for her birthday, Lilly received a great gift, Wild Animal Baby. It's a monthly magazine full of great pictures, stories and more. She loves getting her magazine each month and we read it over and over again!
So, if you're looking for a unique and inexpensive gift, you should check Wild Animal Baby out!