Who am I to disagree with the venerable Sqad? But, pretend this comes from Mrs. C who'll tell you she stopped snoring and mouth-breathing the very night she began using the device.
If you decide to keep using them after trying it, check out Ebay for volume buying. From any store (here in the U.S.) they cost about 40 cents per unit but I was able to buy them for 14 cents apiece on Ebay (but had to buy 150 at a time)...