I didn't realise it was so hard to find a place to stay in Madrid. Let me put this out there and see if anyone can help me.

I'm going to be in Madrid from March 21st to the 31st, 10 nights. I'd like a place within 30 minutes walk of Plaza Mayor (large area), something with a fridge and a stove, one bed and preferably clean. My budget for the 10 nights is 650 Euros. Anybody?