I have made ebay fabric purchases and most of the time, maybe 90%, all is well and I'm very pleased. But, now and then it doesn't work. Either the color in the photo wasn't accurate (dark blue and white in reality, but the ad said black and white) or the quality isn't what I'd hoped. But--the price can't be beat. Just last night I purchased 16 yards from four sellers and with shipping it worked out to $5.75 a yard. Several pieces were ones I couldn't find elsewhere. And with the price of gas....
I have learned to be very careful buying black and white fabric on line because it comes black and cream too often. If color has to be perfect (I'm looking for a light green now), I wouldn't buy from ebay--but from a on-line quilt shop I know is accurate 100% of the time.
Try just a little and see how it goes. Remember, too--up to 8 yards usually ships for $5.