Europe - Buying prepaid cellphone in MAD

I'll be arriving in MAD first thing in the morning on 4/4... work's not paying for this trip, so rather than roam, I have to buy a prepaid phone

Is there any store in the airport or nearby on the metro that anyone can recommend?

In Terminal 1 Baggage Claim there will be person selling prepaid phones for about 25-30 Euro. Comes with 5-10 Euro of service, IIRC.