I work for a non-profit and we have four guitars that were recently donated for our upcoming fundraiser. I am wondering if anyone can help me determine the value for them. They are all signed on the guitar itself, not the pick guard. The two that are encased are signed by Aerosmith and the Rolling Stones. The other two are not encased and were removed from their cases, leaving some sort of black mounting glue on the back of the guitars. Those are signed by Paul McCartney and U2. All have COA's from a reputable company. I appreciate your feedback! Thanks.