When travelling within Europe, there are many low-cost airlines. They tend to fly into airports near the main cities, but this need not be a problem as there are often good bus connections.
One such airline is
ryan air , they are a "no frills" airline and so offer no free inflight service and the price of things to buy onboard is very expensive, so if travelling with them, ensure to bring your own food supplies on board. Also note that the prices they quote on their website do not include a luggage charge for luggage you wish to place in the hold. The price does include carry on luggage.