Seems to be GB£3-£4 per fat quarter here (approx. US$4.65 - $6.20 at today's conversion rates) - increasingly more towards the £4 end
Don't normally expect to pay a premium for fat quarters vs. yardage here - cost is usually just the yardage cost divided by 4
I am one who will make the most of US stores who do international shipping. I can easily pay a half to a third of what I would pay over here as long as I'm careful balancing amounts against the shipping rates. And if there is a sale...