I'm Belgian, and I can tell you this is beer paradise.
A Chimay like those we were drinking on the photos was 2.60
It strongly depends on the place. In some places it will be 2 , others will be even 3.50.
Chimay isn't the only good one at all though. If you get the chance to taste Affligem, do it. That's from the monestry that's right in my neighbourhood. And it has been awarded best beer in the world 2 or 3 times so far.
I think Belgium's best known specialized beers are Leffe, Hoegaarden, Affligem, Chimay, Duvel and Grimbergen.
On a sidenote: I don't like normal beer at all, only specialized ones.