As long as it's wool, is it alright to use? I can't find any flannel sweaters, currently broke, and it's ridiculous to pay $20 for a cloth at the health store.
Also are there other alternatives to use besides flannel?
I see no reason you could not use a sweater. I have used an old army blanket (wool) with good results. Cotton flannel is good for the packs also. Cotton flannel can be found at Walmart in the cloth section and is very cheap.