This guide shows how much each level costs for ALL the upgrades.
Before starting make sure to purchase the Double Cash, Bigger Beacons, Healthy Bananas, FastTrack and Reverse game type
Each upgrade has 13 levels to it. In order to unlock each upgrade level, you must complete all 63 tracks on EASY, MEDIUM, HARD, IMPOPPABLE and REVERSE. In doing so you will unlock Mastery mode for each type of track (i.e. beginner, intermediate, expert). Mastery mode is a game type that allows you to replay each track, but the bloons are stronger, towers are more expensive and rewards are greater.
Popping Power 2-3-4-5-10-12-18-25-35-40-45-50-60
Attack Speed 2-3-4-5-10-12-18-25-32-40-45-50-60
Starting Cash 1-2-4-6-10-12-20-25-32-40-45-50-60
Starting Lives 1-2-4-6-10-12-20-25-32-40-45-50-60
Sell Price 2-2-5-6-8-12-20-25-32-40-45-50-60
Big Bloon Sabatoge 2-3-4-5-7-10-17-35-40-45-50-60-70
Hotter Cooldown 1-2-3-5-7-10-17-35-40-45-50-60-70
Upgrading everything will cost 2209 coins. This is a lot of coins, which means a lot of grinding. Once you have unlocked mastery mode I suggest doing some tracks on that game type. You can buy 5 coins at a time with $750 monkey money. This makes things go a lot faster, so save as much cash and coins as you can