Personally, I hate doing garage sales. No matter how cheap you mark the fabric, you will get people insisting that 50 cents for 10 yards is a fair price. I did one garage sale about 26 years ago, and will never do one again. I get more joy out of donating stuff, especially when I do my taxes.
Unless you really need the money, why not consider donating it to your local Project Linus or Quilt Guild. Project Linus blanketeers make quilts that are given to children in crisis. Some groups also donate quilts to nursing homes, homeless shelters, etc. My local group has donated over 30,000 quilts so far. Some women can afford to donate quilts using their own money to buy fabric. Project Linus also puts together quilt kits using donated fabric so that more quilts can be donated. Many of our most talented quilters are retired and have more time than money and love to quilt and donate their time. Just a thought.