Selling a very rare album

Want to get your thoughts. I'm selling my album collection and I have a rare issue from Jethro Tull named "Hand in Glove" that only 500 were pressed according to disclogs and popsike. The album actually has paper glued on the front and back with Ian Andersons face with a slogan on the front and the song names on the back. It is a double album in mint condition. How would you determine or who would you ask how much something like this is worth?
If you already checked and discogs for the price statistics then why do you ask ? 
If its a bootleg, you won't get much for it.  I bought a Pink Floyd bootleg called "Raving and drooling" from the Animals tour and it is one of the worst recordings I ever heard.  A tin can telephone has better sound.  I paid $40.00 for it, what a waste of money.  If anyone wants it, Ill let it go for $20.00, lol.  I purchased it from discogs.