If you aren't familiar with a rectangular gathered skirt with a waistband, you can follow this tutorial (just use one layer of fabric and your measurmentx 1.5 because the JCrew skirt isn't nearly as full), or find it on Pinterest :)
You will also need a zipper and closures of your choice for this hack.
and this fabric for $8.98 a yard:
If you'll notice, the skirt doesn't have a stitching line along the bottom, this is because it has either a lining or a blind hem. To learn how to do a blind hem, check out this tutorial.
Fabric.com is my go-to online fabric retailer, I've ordered from them numerous times and I know that I can trust their quality, but if you have a place that you can find this cheaper and know it will be good, go for it!