I came to know about Whichbudget, it's a website that allow search for flights by country. I mean you just enter from like "Germany" and to like "Belgium" and you get best offers from all airports between the two countries. That is great. And I was able to arrange a good-price trip to Brussels.

Now I want to arrange another trip to Turkey, but Whichbudget is not helping much this time. And I can't find any other websites that allow "search by country".

Update: Not duplicate to How can I do a “broad” search for flights? as his question is broad to the extent of a state. But my question is broad to the extent of a whole country + less price + "Any Time". If anyone checks whichbudget, he'll understand what I'm saying. Especially that whichbudget allows "Any Time" option, not just +/-3 days.

Does anyone know more similar websites?