I see that you can buy game time with in-game money. How much is it, would I be able to make enough during my trial to buy some? Or is it very expensive?

I don't really have a reliable income at the moment so I'm hoping if I set aside some time every month to earn enough ISK (i think thats the currency) to buy 30 days of time I'll be able to keep playing.

Would this be a possibility?