Okay, this is a tiny tip on how to save money -- not just on trips, but anytime: We used to always buy a magazine for an airplane ride; it seems logical, after all. You have to be at the airport early, and then you can pick up a magazine while you're waiting for your plane to board . . . but magazines have gone sky-high lately -- at $5-6 each, that's a meal!
Now we go to the library before a trip to get our magazines. The small branch library where we usually go almost always has a box of FREE magazines. People donate these because they don't want to keep them, but they don't want to throw them away. Yesterday I even lucked into a couple diabetic cooking magazines, which is very handy since my husband was just diagnosed with the disease. Yesterday my daughter and I went to the library (actually to return the books-on-tape, which we'd uploaded to our iPods for our trip), and we picked up about ten magazines for our family of four to enjoy. If you're not too picky about exactly what you read on the plane, it's a great idea.
Tip 2: (I took this one from Budget Travel magazine)
When your plane flight's done, leave your magazine behind. You're not going to read it again anyway, and the person on the next flight will enjoy it.
The flip-side of that tip: Be the last person off the plane, and look to see who else has left a magazine behind. My husband travels frequently for business, and he often brings home something I wouldn't have considered buying, but often I enjoy them.