Not sure why people think this price move has anything to do with a buyout. Look at this year to date chart:

http://finance.yahoo.com/echarts?s=GDXJ+Interactive#symbol=gdxj;range=ytd;compare=prb.v;indicator=volume;charttype=area;crosshair=on;ohlcvalues=0;logscale=off;source=;

This chart compares junior gold miners to PRB, and they are both moving up together. The good news is that PRB is behaving like a junior producer rather than a junior explorer, since many of the junior explorers have not moved much (they will be the last ones to move).

So, where does that leave us? Once we have the land package sewn up, the 43-101 done, more drill results (especially the drill results from the lake) and a PEA, we should way outperform the junior producers index...thus the best is yet to come.