Don't throw your old baking sheets out because they look a little old or have some residual baking stains on them! Use some old fashioned elbow grease, some baking soda and some peroxide to shine them up and make them look like new again.
Sprinkle them with a layer of baking soda, pour on hydrogen peroxide and sprinkle another layer of baking soda on top. Let it sit for a couple of hours, then wipe off.
When my daughter was younger, she borrowed some of my sheets to take to a friend's house to bake some cookies. When I asked her where my pans were afterwards, she told me her friend's mom had accidentally thrown them away because she thought that they were hers and she thought they looked too old. How rude! Yes, I must admit that ajax and a brillo can be a lot of work sometimes, but if you bake on it and burn stuff into it, the least you can do is try to put some good old fashioned cleaning effort into something before you toss it out. I will always try to clean something up before I give up on it!
Ta ta for now...save money!