This is not a Bison grass vodka. It is a classic crystal clear rye vodka (CEDC - Maspex produces 13 different kind of vodkas under Zubrowka brand). It doesn’t change the fact as Darian wrote that the price/quality ratio is superb especially if you like gentle vodkas.
Here in Germany it's bottled at 37.5% alc./vol, and at its price point (less than 10€ per 0.7l bottle) it's the most pleasant vodka I've tried. Everything cheaper is pretty terrible, and others in the 9-13€ range either have a harsher burn or some clear "off" flavors.