We went to El Viejo Almacen when in BsAs last spring and enjoyed it very much. Dinner was included -- I think the total tab was about $60-70 USD. The meal was very good, and so was the show.

I've heard good things about Esquina Carlos Gardel, but we didn't make it there.

If you want to get the whole tango experience, it might be good to go to a production show one night and a milonga another night.