In order to make the transition back to rags, I found out that I had to have them handy. So I keep a supply beside the kitchen sink in box. In the bathroom, the rag box is a small trash pail under the sink. We found that an old bucket works well out in the barn and tool sheds.
Where do I get rags? Well surely I don't buy them. Yes, I've know people who do, but that's hardy frugal, isn't it? So discarded clothing is my main source. My own clothes go through a progression, starting out as good clothes, slipping down to going to town clothes, then work clothes, and eventually rags. And sometimes the local thrift store discards a bag of clothes rejects, and they become my rags too.
Ever think about grades of rags? Some are better scrub rags, such as worn out bath towels. Old t-shirts make great general purpose rags. Some clothes don't make quality rags, so their rags go out in the barn and work sheds to be used as "disposable" rags for paint, oil, grease, and other messy stuff. They're also good for cleaning up dog barf, cat hairballs, that sort of thing. No need to wash those disposable rags. They go right to the trash. It's a shame that clothing isn't all made out of natural fiber anymore, because those discarded rags could be going into the garden. But alas, the synthetic components don't rot down.
We've successfully made the transition to rags. Hubby no longer looks around for a roll of paper towels, though I do catch him grabbing the toilet paper to clean up a hairball. But the most difficult thing was to train him to throw a used rag into the laundry instead of the trash. Ah, he was trainable! Hurrah! So rags it is, and rags it shall be for my future.