There is a big difference between two types of credits used in this game. You can only use Blue during single-player, and Gold during multiplayer. You can earn these naturally by playing each campaign, and/or you can purchase more with these prices:
Blue Credits
5,000: $1.99
14,000: $4.99
33,000: $9.99
70,000: $19.99
190,000: $49.99
400,000: $99.99
Gold Credits
10,000: $1.99
28,000: $4.99
65,000: $9.99
140,000: $19.99
380,000: $49.99
800,000: $99.99
Tactical, beautiful, and wholly unique, the GOTY-winning sci-fi RTS returns with Homeworld 3. Assume control and battle through fleet combat in dazzling, fully 3D space while the award-winning story unfolds on a galactic scale.