The best way I've found to save on a few particular baking supplies is to buy them in bulk from a restaurant supply store. Strangely enough, there isn't one near me. But, I did find one online.
The supplies I wanted were Parchment Paper and Muffin/Cupcake Liners.
I found both on this site. The parchment worked out to be $44 for 1000 sheets when I tacked on the shipping. Each of the 16 x 24 sheets can be cut in half to make 2 sheets. I bought my first box 13 years ago and I still haven't run out. If you aren't interested in a whole box, you can buy it in packages of 50, or you can split a box with friends like I'm doing and share the cost. I also found muffin liners. They were $6 a box plus $3 or $4 per box for shipping. This works out to about 80 or 90 cents per 100 white liners. At Walmart when I checked last week, 32 were 92 cents!