My daughter and I bought fat quarters. When she was done with her fat quarters, she gave them to me. Luckily we bought different prints.
I forgot where I ordered them from but I had purchased a set of 6" squares specifically cut for an I Spy quilt and I was disappointed with them. They were just cut into squares without taking the print of the fabric into consider when the cuts were made.
I think fat 1/8s is a good idea, and really the 6" squares were too if they had been cut better. I now have a couple of containers of I Spy type fabric that I may never use again.