I have investigated lighted nocks. The version you linked too are constant on and will be on when you are in the stand waiting n the deer. Thee are other versions that turn on when the arrow is shot. I have also came across a memberr from another site that has built their own lighted nocks for crosbows and loves them, but they told me the cost was close to (if I am remembering correctly) $6-8 each when made by yourself.

I will see if I can come up with that info again.