Since those are discontinued, you won't find much market I'm afraid. Best bet is to decide what is the least you would take, and add some above that and see what happens. SWFA may have some on their samplelist that might serve as a guide. Also check online auction sites to see if any are listed. The earliest model with the huge oculars will not likely move as well as the second version.
I disagree with the above comment, discontinued items always increase in price. its a demand and supply thing. whoever want can't get it else you sell it.
I have a pair of these and I believe they are very under rated. Extremely clear optics and built tough. I wouldn't sell mine for anything less than about $800