yeah, my first reaction would be to just beat the ever living shit out of the fucker, or set him up with the police or something.
however, when i stop to think about it, rather than focus on emotions, you have to look out for yourself... if you pull some big time retaliation on him, you're upping the ante, and you might find yourself in a raft of shit.
if it were me, i would get back at him by outsmarting him the next time... and perhaps by doing little things on an occasional basis to make his life a little more special than most people. ya know, things that make his life just a little less pleasant... here are a couple ideas just off the top of my head as i brainstorm:
1) see if you can get his girlfriend/wife pregnant or something. (make sure you get a blow job from the skankiest ho you can find before this to boost your stds)
2) wipe dog shit under his car door handles.
be creative, there are lots of ways to get even without elevating things to baseball bats and guns.
or just let it go, and collect the good karma later in the form of another bigger, better, and more secretive harvest in the future. if this harvest was a huge grow and you were counting on the income it would've brought in, that might be a different story.
sorry for your loss!!