40 is the going rate.
For crushing it, there are two ways to do it. NAturally one is easier, and one is "right."
The quick and dirty way to do it is to crush it in a vice (use wood or something soft to protect the part) until the vac nipple just touches the case. The correct way to do it is to get a "mightyvac" or similar device (one man brake bleeder, etc) and apply vacuum to the vac nipple. Hold the valve up to the light looking through the outlet. Crush the valve in small increments until it takes ~18 in/hg to just crack the valve off the seat (you'll see light through it). 19 is pushing it, and 20" will make the BOV a little too tight and noisy (fluttering).