After spending hours and hours searching every nook that Detroit had to offer, I was tired of picking up huge amounts of ammo because enemies guns that get left around get converted to said ammo if you already own the gun (obviously). 
Since bodies and weapons stay around in the environment for a very long time (360 version), I started making trips back and forth to the local gun merchants.   
Sell a shot gun, go back and pick up another, and repeat. 
 
I must have earned over 10,000 doing that, which of course bought me two more praxis points!  This might be kinda ruining the game pacing... but I hate knowing there are badass abilities locked up inside me that I can't get to!!!  ;D

it's not really ruining the experience if it's the experience you want to have.. i mean, this kind of game is about doing whatever you want, and well if that's what you want then that's what you want :)