I picked my copy up from eBay back in 2010 as I couldn't find it anywhere either. H&S prices can be all over the board as this game is kinda hard to find and I purchased mine from a seller in Great Britain for 4.95GBP (at that time it was $8.23USD).
Zombie: Empirical data's your only man, when formulating a research plan. A soldier's death is never in vain if it makes the formula more plain. A few dozen make a better case for refining that third decimal place. They call me Zombie because I don't sleep, as I slowly struggle to climb this heap, of corpses, data points, and trials, but from the top - I'll see for miles!