That's up to you.
The point I'm making is that there are cheaper options than Momondo, if people have the time to search. This might be with another meta, direct with the airline - or through an agent. I'm not suggesting you do anything - but merely giving people the knowhow that the options are out there.
I think it depends on where you're going. I use momondo frequently, and it's normally the cheapest I can find..but it depends where you're going. And the time of year, etc, etc. I fly normally between Munich and Vancouver, and have most of the times searched on Momondo, which was the cheapest..once or something I found another place that was better. A few times I bought from the actual carrier (Air Canada in this case), because it was the same airline the whole way, and the price was virtually the same. But I found it better than other sites, since it's stays constant in regards to the price, as in it's usually pretty good, for longer. Other sites I normally find a good price once, but then don't end up using it ever again. Maybe it's just a coincidence..but yes.
Expedia is the best for flights <