These may help.
http://www.whichbudget.com/
http://www.skyscanner.net/

Hello all,
I will be playing at the Eurockenness Festival in Belfort France on July 6th, and am going Vejer de la Frontera (flying in through Seville) to visit family for a reunion on July 7th. I am not sure which city would be the most convenient to Belfort, as it is on the border of Germany and Switzerland, and I will be in somewhat of a hurry. Which cities should I consider flying from (Paris, Frankfurt, Basil, Bern)? Also, which airlines are most likely going to offer service to Seville. I did a quick (i.e. 30 seconds) search, and found that not many european airilnes fly in to Seville, or anywhere in Andalucia for that matter.
Any help is appreciated.