I was able to find tickets with Transavia from Paris Orly to Seville for 40 Euro 29 Jan 2014. Its a discount airline.
Disadvantage is it doesn't appear to travel daily (at least in January). Ryannair flies from Paris (Beauvais) same date 39.99 Euro. (I have no idea where Paris Beauvais is (yet)) Prices go up as seat availability goes down so if you book early enough its the cheapest way to go. Si yo fuera tu ... fly with Transavia ... My one experience with Ryannair led me to believe I was in a neverending flying television commercial.
Transavia
http://www.transavia.com/hv/main/splash
Ryannair
http://www.ryanair.com/
The airport in Madrid is called Barajas (MAD). There are 4 terminals. T1, T2, and T3 are connected while T4 is reached via shuttle.
Madrid Airport (MAD)
http://www.aena-aeropuertos.es/csee/Satellite/Aeropuerto-Madrid-Barajas/en/
Information about the shuttle to T4 is located here
http://www.aena-aeropuertos.es/csee...554331229//Connections-between-terminals.html
Connections to Madrid include subway (Metro) and light rail transit (Cercanius). The Metro has stations at T2 and T4. The trains run every 6 - 12 minutes. Cercanius has a station at T4 and runs every 30 minutes.
Madrid Metro
http://www.metromadrid.es/en/index.html
Madrid Metro Map
http://www.metromadrid.es/export/sites/metro/comun/documentos/planos/Planomayo2013.pdf
Madrid Cercanius (operated by Renfe).
http://www.renfe.com/viajeros/cercanias/madrid/index.html
Madrid has two major train stations; Puerto de Atocha and Chamartin. You will need to know which station your train is leaving from.
Puerto de Atocha is reached by Metro. Take line 8 from airport T1-T2-T3 or T4 to Nuevos Ministerios; line 6 to Cuatro Caminos; and, line 1 to Renfe Atocha
Chamartin is reached by Metro. Take line 8 from airport T1-T2-T3 or T4 to Mar de Cristal; and, line 4 to Pinar de Chamartin.
The Cercanius train goes directly from T4 to Chamartin and subsequently to Puerto Atocha. Since it operates (vice every 6 minutes for Metro) every half hour.
There is a free shuttle to T4 from the other terminals (edited)