The sock/pantyhose thing is mostly to lessen the current for adult fish who have problems with the current(like halfmoons who have longer tails).
If you can't buy one online, you can makeone from things you might already have or can buy at petsmart.
you need(i think) an air pump, some airline tubing, a plastic tube or pvc pipe(i'm going to me using a plastic tube my glowsticks came in because it has a 'cap' so i can keep the airhose in there without an airstone or sealent) and then the actual sponge......don't quote meon this though as it just what i can kinda remember, i can look for the guide to make one if you like.
Many people have just done filterless spawns with success though.