http://www.quiltappraisers.org/findAppraiser.html
Written appraisals used for insurance purposes cost more - I've seen $35-65 per quilt, but if you had a pile of quilts, and just wanted ballpark figures before you put them up for sale, then I'm sure you could work out an hourly or lower per quilt charge.
The appraiser would (should) also have recommendations for you on reputable auction houses and dealers. eBay is also an option, but it's ...fluid.
But I wouldn't mention you wanted to sell them until after the appraisal.
While I'm not making any statements, many appraisers are also collectors. Just saying. ;) ;) ;)
Good luck. If you ever take pictures of them, please come back and share them with the board here. We LOVE to see old quilts.