Basically, these toys are just made by cutting pieces of felt into food shapes and stitching a little catnip into them using embroidery thread. So you can easily experiment with materials and patterns to find the toy that your cat enjoys most.
As far as the durability of these toys go, I think they will certainly be around long enough to get quite a few good plays out of them, but you could also buy a more dense wool felt if you want them to last a little longer. All good toys come to an end eventually though, and I have a few furry mouse toys that have been taken down to the plastic skeletons to prove it!
Of course if you really want to spoil them you can pour them a saucer of wine to wash that junk food down with, but that’s up to you. Bon appétit!