Easier than it sounds, guys!
I unlocked this in the first Challenge Zoo the game offers you. I simply spent some time focusing on a couple other Challenge Zoo achievements (which there are a couple of GREAT solutions for!) I unlocked it naturally a lot faster than I thought I did.
Don't forget to research upgrades from the pause menu too! I completely forgot about that functionality for a bit and probably lost out on time. The advertising upgrades are especially useful for this particular achievement.
Good luck, and happy hunting! 🍻