Actually, I have seen only one shop in the game that needs real money, but I have never used it. 
It also has a system that allows players to attack each other everywhere, but its considered as a crime. Then you will become wanted and people are given a prize if they kill you.
But there is a beginner protection, so when you start the game, you won't be killed.

My computer has become too slow to play the game T_T but I recommend it.

Shortly, it is 99,9% free :)