since fabrics vary from $1 a yard- right on up...
figure 8-12 yards for the top (depending on the pattern chosen- and of course you can make it easy- big block= in theory make a queen for less fabric- but for a quilt with a block = many pieces- it takes alot more than people realize.
then you have your backing/batting/thread-
you can make a quilt for anywhere from $20 right on up to thousands--
a tuning 20 quilt- with borders to make it into a queen takes- 20 fat quarters (and if you buy fq's instead of yardage figure about $2- $2.75 each for fq's- then another 3 yards or so for borders-
if you use a wide back (108"-118") you need 3 yards=(108") to back it- wide backs can be found from anywhere between $8.99 up to $25 (more or less)
of course you can pick up lesser fabrics-
there are shops that advertise $20 quilts-(for the top)
it can get a bit overwhelming when you look at a pattern that calls for 12-20 yards of fabric-just for the top- i guess that's why i tend to do scrappi-er quilts- work from my stash- watch yardsales- thrift stores- sales-
if i actually have to go buy yardage it's only a yard or 2 (3 if i want a continuous border)
it takes alot of fabric to piece a quilt
i've made quilts for as little as $60 and for as much as $700 (yes in materials-before quilting)it's all relative to what you are doing