Alphabet Coloring Pages - great idea for baby shower! Print all the letters on cardstock or heavier paper. Have guests color the pages anyway they like and sign a message for baby on the back. Have the pages laminated and bound into a keepsake book!
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 :)