I just ordered slides from ebay. They were 3.75 for 72. This is the best price I could find.
Also, the instructions I have only require one slide. Obviously by doing the "sandwich" technique, you would only get 36 ornaments but doing then single you would get 72. I be an accountant, can you tell??? LOL
Here are the instruction I am using (posted by crzy2prple):
"I soaked the dominos in bleach a couple of days (mason jar with the lid screwed on). Stamped with Stazon, let dry (you can use a heat gun, but the domino will get very hot), colored with colored pencils, then sprayed with Krylon Triple-Thick Crystal Clear Glaze. Make sure you are not to close when spraying, it will run if you are. Then I used E6000 (adhesive I found at Hobby Lobby, they keep it in the front by the registars or you can use crystal effects to glue the pin back on it. HTH"
Here is her post:
Gallery at Splitcoaststampers
Hope this helps.