Look in a used bookstore or a Salvation Army for good books on the cheap. Our local SA has a nice selection of books--I even found an Italian vegetarian cookbook--perfect for my college-age, Italian vegetarian daughter!
They also have toys. If you were able to find one, casually looking around, a
lego table to swap out occasionally with the train table might be a good find. Just to keep things fresh.
For magazines, ones that are a couple months old aren't so bad, especially things like HGTV (I LOVE reading this at the doctor's office!). Standards like Reader's Digest and People are good, too. One office I wait in has local (state) magazines, which are fun for me, since we just moved here. Magazines that irritate me, personally are: things like Time (gets dated very quickly), Golf Digest or another specialty magazine, and health type magazines--these just feel like getting nagged at, for some reason. But, it's like anything else--if you keep on top of them, take our old or battered issues, and definitely if you have a source for recent issues, use it. Again, it's not so much about spending a lot of money as taking care of the space.
Do some magazines offer free subscriptions to offices? It might be worth looking into...