Penny Pincher

Difficulty: Easy

This Achievement can be done at any level, including Adventure Mode, but only if enough coins are dropped. The best levels to do so are Survival: Endless because large waves of zombies arrive, however, you can't let any disappear, or this achievement will not count. Playing the Last Stand Mini-game and using Marigolds or a Gold Magnet would be a good example. Another would be playing Whack a Zombie (or level 2-5) because the zombies drop coins very often in that Mini-game. It's easy to get this Achievement in Zen Garden (the more plants you have, the easier you can get it). Another excellent way to get this achievement is through Wall-nut Bowling. Just wait for the screen to be filled with zombies, then send a few Wall-nuts through to make combos and therefore earn coins.

Note: Diamonds will also count for the achievement.

Strategy
You can easily earn this in Zen Garden and Survival: Endless.

Trivia

 * The name of this achievement is a reference to "penny pinchers"; people who are careful with money and pinch it before letting it on a surface.