Find a GOOD Auctioneer...one who knows something about stamps and who advertises well. We sell them often. The advantage is that you will multiple collectors bidding against one another.
We sold a small collection for someone who had been offered around $200 by a dealer. We broke it up and sold it in “pieces” for our client for a total of nearly $2000. May take a little legwork, but should be worth it.
thanks much!