Agree shares245 that BTU is a buy at 5$. Would personally buy multiple thousands of BTU shares at such a low price, and consider my very lucky to have done so...
The only issue is where the "bottom" in BTU share price cost is.. to me 5$/share for BTU seems like a 6-sigma event - I don't expect it to happen, it's simply too "extreme of a condition" to have any statistical validity unless there is a "market melt-down" across all commodities. If that's the case, then there are no "safe havens" in commodities. Won't matter what commodity you buy. If BTU gets to $5/share in the next two years, all commodity buyers will be sucking red-ink.
This may happen, but I don't think that it will unless the "asteroid" hits the earth. Barring such an off-the-wall event, seems to me that BTU will only go below 15.5/share if world-wide CO2 caps are put in place. I don't see that happening - too many competing interests in play.