I have saved myself a lot of money by learning how to do this. Often when sewing I'll have to get a small piece of fabric that is a very specific color. Recently I needed fold over elastic and I needed it that day. The only fold over elastic I could find in the store was in black and white. Rather than buying some online and paying for shipping and waiting for over a week for it to come in the mail I bought some fabric dye and made my own in the perfect shade. For a FANTASTIC color guide for mixing RIT colors look here.
Plus, people will be super impressed when you tell someone you 'hand dyed' it. It just so sounds so much more artsy and creative!
Another thing I forgot to mention in the video is that if your fabric is not as saturated as you'd like try letting it dry completely then re-dye. This definitely has worked for me. Another neat idea that I'll be trying soon is tea dying for an antique look! I can't wait to show you that one.
Top photo courtesy of Divânia Nogueira.