i have used regular prints wide 108" backings, 110" wide flannels and 116" wide batiks. the flannel was the only one that was not as heavy as what i usually buy but it still worked great and was a good quality, did not pill after a few washes. the batiks are the same as 45" wide bali batiks. i love using wide backs and have had no problems with sub-standard quality. and i am very picky about fabrics!
2 sources for wide backs are fabric.com AND quiltbacks.com but if you type wide quilt backs into your search you will find lots of shops that carry them, and just like everywhere some are better quality some not so good...shop at a reputable shop and if in doubt contact them and ask for a swatch so you can check it out before you buy. it is a very cost effective way to go...3 yds of 116" wide fabric gives you 116"x 108" ...so cost wise i can back a quilt for about 1/2 what it would cost for me to buy 9 yards of 45" wide fabric.