thousands of bolts
quilt fabric closeouts
whittles fabric
and
fabric.com with a coupon and free shipping is very inexpensive.
also
connecting threads but i don't shop there i don't like their fabric but many people on this forum do and you can find fabric for under $3 a yard.
then of course, all the shops that offer coupons, for example rented mule has a coupon now and you can buy fabric for around $5.50 a yard.
nancys notions has hoffman batiks on sale for $6.50.
its just a matter of knowing when and where to shop online and to sign up for the newsletters for the coupon codes.