A lot of my early quilts were practically free. You can see they are very scrappy, and small (which helps a lot!). Also several older women who no longer sew had gifted me their old fabrics, and someone even gave me a queen-size batting.
The fish quilt was made from scraps leftover from different clothing projects over the years, and backed with something my mother gave me out of her stash. The batting was the only money I paid out of pocket for it.
The sampler was made with gifted fabrics, or some that came from a box of fabric and scraps I bought for $5 at a thrift store. Batting was the only cost on that one. The sashing was something I traded sewing patterns for. The backing was mostly pieced from old clothing.
Overall I'd say I've made four or five quilts that were similarly inexpensive. I gave the elephant one at a baby shower. It cost under $3 and thread, because I used batting scraps my aunt gave me and did it in a quilt as you go method, with a center panel that came off of the $1 a yard remnant table, and other fabrics that had been given to me. The binding I had to go and purchase; it was about 75 cents worth of fabric from wal-mart. Of all of my "cheap" quilts, that one came out looking the most put-together.