Just a quick warning though. A lot of those flights are not originating from the city or main airports. For instance, the "Brussels" flight they suggest taking is from an airport that is one hour away from Brussels (in Charleroi). It means that you will need to spend some more money to get to the city centres. These additional costs from "low cost" airports to the cities do add up to a significant amount on that entire itinerary. Just something to keep in mind.