I don't know how I have made cookies all these years without this item. I didn't even know they existed until a few weeks ago when a friend of mine mentioned them to me. I'm sold! Never will I bake cookies without them again. How have I lived without silicone liners for so long. I have baked three different batches of cookies on these and LOVE, LOVE, LOVE them. I couldn't burn the bottoms if I tried. Seriously. These are by Technique. I ordered them from QVC. Right now they have them listed in their clearance section for less than $20 for both! One is a 13" x 18" aluminized steel cookie sheet with silicone liner. The other is a 9" x 13" pan with liner. They have measurements along the side, and there's no need for cooking spray. I made peanut butter and sugar cookies on them, and there was no sticking whatsoever.
I noticed they also sell a two pack of just the larger size as well. I believe that was around $30 if I recall correctly. Definitely a great present for yourself or another baker. If you want to splurge on something nice for yourself, I highly recommend these baking sheets!
Here's the link if you're interested: http://www.qvc.com/qic/qvcapp.aspx/view.2/app.detail/params.item.K19238.desc.Technique-Aluminized-Steel-2-pc-Cookie-Pan-Setwith-Liners