Convinced me to horde my coal till the very end!
A rational part of me says to hoard my coal, but on the other hand some people have gotten so hardcore with the trading/hoarding/multiple account coal farming that I know my chances of winning anything are effectively nonexistent.
But yeah, you might have better luck at the end of the sale bargaining off your coal to the desperate. Personally I'm pretty much going to buy anything I want that's reasonably cheap (yay new job! Yay Christmas money!), and I doubt I'll ever have enough coal to bargain for the more expensive stuff I'd actually want.