I think that depends on what you're making. If you're trying to duplicate ready-made clothes, you'll actually pay more to do it yourself. The upside is you get a garment that actually fits you, in the colors and fabrics you like. If you're creating your own clothing designs and sewing up one-of-a-kind masterpieces, then you'll save money doing it yourself (vs. hiring a seamstress or designer to do it for you)
If you're copying high-end designer pieces, it may save you money to do it yourself. But the couture fabrics cost much more than the cottons and blends you can get at your local JoAnn.
Some ways I've found to save money sewing my own clothes include shopping online for fabric, learning to draft my own patterns, and upcycling fabric and findings from thrift stores, yard sales and my own closet.
And shopping off-the-rack just doesn't come close to the joy you get making your own works of art to wear.
