I used to fly my C42 from Damyns hall to L2K a fair bit and if I flew at 85kts which is about 16 ltrs an hour L2K was about an hour. Thats there and back for £32.00.
Drawback on mogas is about 50p a ltr and with a 70ltr tank thats £35 back.
You can do something similar in many bigger planes. In my TB20 (say 150kt TAS), flying from somewhere on the s. coast to Le Touquet and departing with full tanks, the drawback claim (about 330 litres) will also more than cover the entire trip.
The catch is that you can do this only once - until the tank content on which the drawback claim was made is exhausted on other flights.