It looks to be in good condition. The spots on the boiler are probably water spots. You might try a little Carnauba wax in a spot to see if it shines up. The boiler paint looks original. The frame looks like a very nice repaint, but it's hard to say for sure. I'm surprised that the motor says "Standard Locomotive" instead of "Bild-a-Loco". I wonder if the pickup plate was replaced? I notice that members of this forum don't like to quote values on items, especially to folks looking to sell. A full Blue Comet set usually demands more than the pieces do separately from what I have seen. Greenberg does say that the Nickel trim is more rare. I have seen a few though. There are a number of places to find recent sales prices. You can search completed sales on eBay. Live Auctioneers will show prices if you have an account. Worthpoint charges a fee and of course there are the Greenberg guides. My guess is that this one is worth between $800 and $1200. One just like yours sold recently for $990 with boxes.
George
