Monkey Town

Monkey Town was originally the final upgrade of Path 1 for the Monkey Village. It used to cost $25500 on Easy, $30000 on Medium, and $32400 on Hard. However, due to an update on March 22, 2012, it became the 3rd upgrade on Path 1, costing $8500 on Easy, $10000 on Medium and $10800 on Hard instead. The cost of Impoppable is $12000.

All bloons popped by towers in its radius earn 50% more cash per pop. This includes when the tower is upgraded to High Energy Beacon. This upgrade increases the range of the Monkey Village.

BTD Battles
Due to the fact that popping bloons won't award you money in Bloons TD Battles, its effect was altered and it will instead allow all bloon groups to give you back 20% more income. However, in Defend mode, it will not give the 20% bonus to the income boosts.

Trivia

 * Combining this with Double Cash would allow towers within the Monkey Village's range to generate the maximum amount of cash possible (2.5 times more cash earned per pop).
 * This upgrade can be bought on Deflation Mode: however, except increasing range, it has no effect.