My only experience is in Indonesia. There Honda dealerships only sell new bikes as you mentioned but each dealership had another outlet in town under a different name where the used bikes where sold.????
Doesn't seem logical that they would go to auction as that may not yield enough but they may do. There are two types of auction. One for bike up to 150cc which are held every week, i believe, and one for bike over `150 which are either once every 2 or 4 weeks.
64 dollar question? Where is the over 150 auction site.
Maybe Mark at BSR Bike shop can help you?