Here is the only one I've ever seen sold. At that time 5* premades were selling for roughly 5k CE as vanillas. It's hard to say what one would go for at auction today. There are a lot of variables involved but I would say somewhere between 10-15k ce wouldn't be unreasonable, maybe more if you got a perfect storm of bidders.
http://forums.spiralknights.com/en/node/6806
Here is the only one I've ever seen sold. At that time 5* premades were selling for roughly 5k CE as vanillas. It's hard to say what one would go for at auction today. There are a lot of variables involved but I would say somewhere between 10-15k ce wouldn't be unreasonable, maybe more if you got a perfect storm of bidders.