Costly Upgrades

"Beat Monkey Lane Hard Difficulty. The catch? The cost of upgrades is multiplied by their tier. Tier 2 upgrades cost twice as much, Tier 3 upgrades cost three times as much and so on. Monkey Villages disabled for extra difficulty. Start with a free Banana Farm which is unaffected by the cost increases to help you save up for the expensive upgrades."

- Special Mission Description

The description says it all.

Overview
This Special Mission is unlocked at Rank 55. Upon completing this Special Mission, you get 750 Monkey Money and 100 Awesome Points. Special Agents are disabled, so they can't help you out.

Achievements
There's more than one Achievement that can be earned from this Special Mission! The total amount of AP you can get from this Mission's Achievements is 500!
 * Costly Upgrades - Beat the Costly Upgrades Special Mission. Reward: 100AP (as I stated above).
 * Expensive Farming - Upgrade a Banana Farm (not the free one) to 5/2 in the Costly Upgrades Special Mission. Reward: 150AP.
 * Costly Upgrades Pro - Beat the Costly Upgrades Special Mission with the only cash-generating tower being the free Banana Farm! Reward: 250AP.