saw this and thought it was pretty cool way for people to trade in their bikes

http://theproscloset.com/trade/

here's a video on it too

https://youtu.be/sk8fB-HM-gM

The Pro's Closet is in Boulder and they do a ton of ebay sales of bikes and bike parts.  for this trade up program looks like they work with local retailer partners and people can bring their bike and trade-in voucher for credit towards a new bike at that shop.