Trying to compare one quilt top or even one quilt to another is sometimes like comparing apples and oranges. There is so much deviation in the quality of materials and workmanship, it is nearly impossible to assign value, especially based on an internet picture. Appraisers will not even appraise quilt tops in person, as they generally have a lower value than a finished quilt.
If you are selling, you'll have to figure out what is the lowest amount you will accept. Price the item a little higher to insure that amount. If the item does not sell at that price, be prepared to lower the amount. Take into account what you paid for it, if anything, and don't expect a high return. Prices seem to be weakening right now, on eBay. However, quilt tops in good condition are always in demand, especially by foreign buyers.
Good luck. Keep us posted.