It's a set of units called Battleforce, just enough to get you starting the game. Some races are cheaper to collect, because there are tricks and methods to "convert" a cheaper unit into the expensive one.

To be on the safe side, do read through the codex (rule books) of different races available if you want to start playing the game, or any information you can find online/offline. This is to get an idea of what are they about, or generally what is this game about, so you don't regret buying them.