The only way to know for sure is to have a Stamp Appraiser look at your stamps to ensure they are authentic. If you like I can help you get list of appraisers in your area.
I think what they meant was you can contact a Large Auction House, you tell them you want to list them for sale at their auction. They will want to see the stamps to authenticate them before they list them for you. If they are authentic then they will tell you what they expect they might sell for and what percentage they get of the sale.
Would you like me to get you a list of auction houses you might get in contact with, some may or may not be interested in selling these but it is worth a try.
I will need to know what town and state you are in.
I will get a list together for you, I will be back with that as soon as possible.