Another great Montessori book: This one's more indepth. It also has a cool pictorial timeline to help me know what developmental mini-milestones are next so I can think of games and projects James will find most interesting.
You can order a box of books from this site for $12.99. They will range from toddler to young adult books. Each box contains approximately 150 books (give or take). You can also order more age/grade specific books, but it costs a bit more. There is now an advisory on their site that due to high demand, boxes may not ship for up to 5 weeks, but for $12.99, thats a small price to pay :)