I would think ebay is a good place for custom builders to troll for customers. Some people do have a lot more money than others and are willing to pay asking prices when the see something that they like. Would you object if someone paid you more than the usual asking price?
I see several overpriced Ambroid kits every time I go to ebay - for crappy kits that were hard to build and later became available in plastic. Anyone else ever build the ACF covered hopper? With the screen roof walk?
It looks like some dealers put the entire inventory of their basement shops online.
It looks like every brass detail part ever made is on ebay.
