The value of whatever in this world is the agreement between a "willing" seller and a "willing" buyer. Then the seller is always trying to skew the price to the "higher" side and the buyer will skew it to the "lower" side. That is the nature of economics of human beings. That said you need to figure out what you have first. Just a "bunch of airplanes" does not give any information as to what value they are. How can anyone tell you how much they are worth without knowing what they are? You need to do your homework first. Find out in detail what you have on hand, the condition of the items and take detail pictures. Then post them on auction sites like eBay or Craiglist or where ever you have access. Maybe a local club or or contact some club officials. Then you have to convince potential buyers what you have is worth the price you are asking.