... I 'suspect' that occasionaly items on ebay are 'bid-up' to make others believe there is a high demand. One example I saw not too long ago, was a 10,000 franc Central African banknote going for prices well above book. Then I looked at the buyers and found one buyer was buying them all up at higher prices. Next, I would see him bailing out once the price was run up. He and the seller had LOTS of common feedbacks. Maybe this guy just liked those notes....

Point is ... it may be misleading to base prices on a few eBay sales. Make sure there is in fact a market like Archie has pointed out.