I had heard of other people using towels, and figured I'd give it a try. But the only towels I could find when I was out were $2-3 a pop, plus I had to buy velco. AND I don't have a sewing machine, so it would be a lot of annoying hand stitching. So I found another great source for the pads...
Specifically, mens, calf height tube socks. They were $6 for 6 pairs.. so 50 cents a pad! These were Hanes - you could probably find them cheaper. With some careful cutting of the socks, you can make a cheap, washable pads for your swiffer.
Step 1: Remove the scrubber pad (optional)
Step 2: Make the first cut
Make a short cut in the middle of the swiffer, about 1/2 the size the swiffer. Err on the short side. You can always make it longer, but we want the sock to be snug!