I have been struggling with this as well. When I heard that Amazon had bought Fabric.com, I thought that meant there would be an option at the "pay section" where I could click Amazon. That is not the case...it is either PayPal or enter a credit card number. I hope they add the Amazon click soon, as ....how do I say this....we, meaning my husband mainly, trusts Amazon.com, whereas we aren't so trusting of other places. In the last 3 years we had two "folks" using our credit card numbers, and we had to cancel and start the credit cards over.
I can, however, go to Amazon and buy most of the fabric I have wanted, but it seemed to be buying one piece at a time. Each time I have done that, I had about six fabrics I wanted, and I just didn't want to do it as six orders. It seemed like I was paying postage for each separately, and at a higher cost.
Now that I have read this, I think I need to go investigate this farther. It has been a week since I looked at either site for fabric. Off to look at fabric and compare.
Dina