GNT is the token of the Golem Network which is an ERC20 token. You can use GNT to pay for the rental of the computing power that you need. However, if you are a provider, you can set your price preference of what you think is most suitable. Since Golem is a market place, it is expected that the buy and sell price of computer powers will eventually reach equilibrium.
Interested to buy Golem (GNT) ? Check the Market Now: https://www.bitkub.com/market/GNT