BomBom Comic and Takara offered special clear version of Robotman Ace call Ghost Robotman and repaint version of MicroStation call AcroStation as contest prizes.  Both items were extremely limited and very difficult to obtain due to the fact that they were not available in store and only giving out to few lucky winners.

Ghost Robotman

Ghost Robotman picture, courtesy of Renji Matsumoto (MicroWorld), uses here with permission.  

AcroStation

AcroStation picture came from Yahoo Japan Auction.