Tablets

My son's bday is coming up and I wanted to get him a tablet. I am not the most tech savvy person so I am looking for some advice on what would be a good buy for an 8 year old. I would like parental controls for it and it would be nice to get one that is educational, something that he can read books and play games that can help him with school tasks. Thanks for the help anyone can provide. Oh, and I am not looking to break the bank one that is economical, I have a hard time justifying paying 400+ for a tablet to give to an 8 year old.