I use parchment paper... I'm to ocheap to buy the inserts.
Depending on what I have dehydrated previously, I can usually get three or four uses out of each cut out.

If it's herbs, I generally write on the paper what it is... as when certain herbs dry out they resemble each other. But with the cukes, I'll need new paper next time because of their high water content. Halfway through the process I move the cuke peelings around because they will tend to stick to the paper.