I've noticed that Schwinn holds their value very well. But what makes others valuable? Are there other brands that do? Does it matter if all the parts are original? I also noticed that racing bikes sell for much more than others do--why is that? I saw some vintage Schwinns on Ebay for around $1500! Why can't my pretty little mixte be worth that much?! BTW, what would be the value of my Batavus if I sold it?