I'm not a spinner, but am dieing to learn! I bought a drop spindle and some wool and learning to spin with the spindle. But now I really want a spinning wheel, too.
You can save money by purchasing your the wool or roving and spinning and dyeing the yarn yourself. But it's not a lot of savings and you will spend a lot of time in the process. I know that it will save me money in two ways. First, the roving (wool that has been prepared and ready for spinning) I bought was a little cheaper than the same quantity (by weight) of yarn that someone else has spun and dyed. Second, it will slow me down so I'm not knitting up my store bought yarn and going to buy more yarn.
But spinning, I think, is something that you either love to do or you learn to hate. I'm the kind of person that generally enjoys doing that sort of thing.