It depends on what you want to use this fabric for.
If you want to cut pieces/strips/shapes and use in a top, you could get 1/2-1 yard increments of many different colors.
If you want to use the fabric for backing and binding, 3+ yards would be required. It depends on if you are making a lap size project or a queen. My one and only queen needed almost 8 yards for the backing alone, but it needed to be pieced. It wasn't 108" wide like some fabric is now.
I hope this is within two hours. I seem to be having problems with basic math and can't figure out 18-12. Especially since that sounds like 6 oclock and it's 5:30 here. But, I'm tired, so I couldn't calculate my way out of a paper bag either.
Good luck with your purchase. If you buy stuff, you have to show us so we can enjoy your fabric with yoU!!
8)