I've purchased fabric, but never more then about $80 so never had to pay duty.
That being said, I'm also a needleworker and when I've ordered (or even received as a gift) something over the $100 I've had to pay duty.
I just can't remember what the amount is that you can have up to without paying duty, you should be able to google it.
BTW, it's definitely worth it, our fabric locally is $18.95/metre...so even if duty was involved it would still be cheaper.