How important is it for the binding strips to be cut on the bias? Would you buy the same amount of fabric to make bias strips as you would for cross grain strips? Thank you for your help! Your website has been very valuable.
If you're applying binding to straight edges, you can use either bias or non-bias binding (cross grain binding).
If you're applying binding to curved edges, I would suggest using bias binding. Bias binding stretches a lot, so it's easier to shape the binding around the curves.
You do need more fabric if you're cutting bias strips. For example, say your quilt measures 200" all the way around, and you want to cut 2 1/2" strips. You'd need 1/3 yard for non-bias strips and 3/4 yard for bias strips.
Whether you're buying fabric for bias or non-bias binding, always buy more than you need. If you should make a mistake, and we all do, you'll have the extra fabric on hand. Popular fabrics sell out quickly. So, be sure to buy it while you can.