Your covers seem to have an asking price of anywhere between $10-$15 each on the low side to 20 Pounds each at the site linked below. You can find them on
ebay and Hipstamp if you would like to establish some values for yourself. You could sell them one at a time or sell the whole lot at once perhaps as an auction lot. Much less work to sell the entire lot. Don't expect to get 76 x 20 Pounds though. An appraisal IMHO seems a bit of overkill. They are not uncommon.
https://www.buckinghamcovers.com/sh...C&shownum=48