- Of course there are the second hand stores, be sure to check often and read the labels. Don't pay too much.
- You can trade with friends, this works well for teen clothing too.
- At garage sales sweaters are very often knitted a portion of the way and given up on so you can get a whole sweater's worth of yarn for a few dollars. Just unravel it.
- Sometimes very chunky wool hand knit sweaters that have poor design to them can be bought at second hand shops and unraveled. This is quite a bit of work but at the going rate wool per skein it may be well worth it if you have more time than money.
- A new source I discovered was a surplus store for housewares similar to T.J. Maxx. They had cashmere skeins for about ten dollars each. Can't tell you why.
- Box stores have cheap wool but that isn't as much fun to find or environmentally friendly.