If you need clothes tailored in Madrid, Spain then check out the Taller de Costura at Buenavista,9 in Lavapies. I love them, they are super sweet. Their dog can seem ferocious but he is all bark and no bite. Tip: he doesn’t like it when he can’t see your eyes so take off your sunglasses when you visit, it will calm him down. I also will occasionally bring him a little treat to get on his good side.
I have had all kinds of work done at this shop and never paid over 10€ for a job. Plus they are super friendly and help you to feel comfortable practicing your Spanish.
I have never had anything come back badly tailored and when not in a rush most items are ready in 4-7 days. They can get pretty busy but if you live in the neighborhood it is definitely worth it to check them out.
From here to home and beyond... 
Thanks for the info, I was looking at getting something tailored here. Do you know if they have a seamstress as well? (I want to get a dress made, I’d buy the fabric myself.)
Yes they have a seamstress but I’m not sure prices as I’ve only had things mended. But the place is always filled for both services.
are there any mens tailors in that area?
If you need something fixed, this is the place but if you want something custom made then I’m not sure. Try a quick search for sastreria in yelp? A few came up but I’m not sure about their reputation.