TexasCHLforum.com

I normally book through Expedia or the airline directly and have no surprises. Including international flights.
But stay away from the scam sites like Priceline or Kayak. They use bait-n-switch tactics to lure you in, collect all your information and then as you click "Finalize payment" (or similar), they pop up a message "sorry, the prices has changed since you looked last time" and they show prices usually N-times higher. Never had any luck there, whether with domestic or international tickets.
So I stick with reputable companies.
YMMV