there are vast differences in appraisals- if you take one of your quilts to a 'certified quilt appraiser' you will receive an (insurance appraisal) the amount the appraiser feels it should be insured for- what it would take to replace it--
it is generally far above a market value....market values fluctuate (alot) are dependant on the area (location matters) and the economy...on the antiques roadshow they (generally) give you the appraisal based on what similar items have sold for at auction recently- not necessarily what you should insure it for if you have no intension of selling it.
i have a quilt with an insurance appraisal of $3700...the market value however is a low $650!!! (which is actually less than the fabrics in the quilt) so i am not apt to sell it before the market/economy regains some momentum. but if i leave it to one of my granddaughter's with the insurance appraisal 50 years from now it may be worth closer to that...or it may only be worth $50...you just never know where the market is going to go