Well considering that event tokens are 60 supply tokens to craft, and a supply tokens are 1:2 with EC, the price of 1 event token is roughly 120 EC. However, because there are other ways of gaining it the price drops down by 20-40 EC per token (or even more depending on seller). They are however pricey and in the end do not affect your game-play in any sort of way. My advice would be get your necessary things like gears/levels etc first and then worry about the tokens.