There's a tutorial on how to do them on AdorableApplique, I'll add the link.
First answer no I have not made the fruit towel toppers.
Second answer it depends on where you live in the USA you can find it at most party supply stores in the gift wrap section
I believe overseas it is harder to come by
I have added a link so that you can have a wealth of info including purchasing Mylar, now remember you only want to buy irredescent Mylar not the colored (dyed) type the dye washes out on laundered items.