Hello: You will probably not find cheap fares right now. They seem to have been taken about one to two months ago. It will probably be about 70 euros right now each way. Go to
www.Iberia.com . Type in your itineary, then after flights show up, look at the bottom right hand side and you will find two buttons 'restricted or 'unrestricted. The restricted fares are the less expensive fares. If your search comes up with only higher priced fares, they have sold all the less expensive fars. Spain Air seems to have less expensive flights as well. good luck