Gold ingame

The game is completely free. Users can purchase gold and other things for in-game play to gain an advantage for their country.

    Gold can be bought in game with real life money.
    Gold bonus is where you collect your gold from other citizens that you have brought in the game.
    Health kits, energy bars can be purchased with in-game Gold.

    Gold can also be obtained by gaining Medals or by exchanging Country Currency at the Monetary
    Market

    I recommend using Gold at start to upgrade one food factory and one weapon factory at Level 2 so
    that you can upgrade your Town Center to Level 3.

GOLD BONUS

This page, viewable from the Gold and Extras menu section, is where users go to collect the rewards that they have earned from inviting citizens. It is also the place where they can track their invited friends.
A citizen earns a Gold Bonus after a citizen they have invited does one of the following:

• Buys Gold (excluding Gold Offers).
• Gets a reward (level up or achieve an achievement)

Getting bonus

You will get an amount of gold that is 10% of the reward the citizen you invited got.

• Earning one of the following achievements ( 5 GOLD):
  • Hard Worker
  • Congress member
  • President
  • Media Mogul
  • Battle Hero
  • Campaign hero
  • Resistance Hero
  • Super Soldier
  • Society Builder
  • Mercenary
  • Top Fighter
  • True Patriot
• Leveling up ( 1 GOLD) 

Collecting bonus

You need to collect gold manually. When a gold bonus is waiting to be collected, an alert will be sent informing them that there is gold available to be collected. All gold must be collected within 30 days, or it will disappear.
A list of the total gold that they have earned from each citizen is viewable from this page, too.

source: http://wiki.erepublik.com/