Like GW1, Piob. No fees whatsoever. Just some store stuff, like one more character slot for 5€ and alike. And like I said, you can even get that for free now by just trading gold for gems. Of course, there will be people who buy gems for real money and maybe they count on that. Such people exist, a lot of them (see: browser based stupid simple games where some people pay -- literally -- thousands of Euros, or $, per month). But it worked for GW1 already. Mabye they're just that good in keeping costs down.
FF, are you playing too? Ingame nick?