I like the sound of the class Napoleon went to in La Catedral, not been there myself, but it sounds like how tango should be taught. These days there is a big emphasis on moves, and trying to do stage tango. If you can walk well, lead with your body not your arms, and feel the music, you need little else.
I am not saying necessaraly that price and quality are in line, but there are few, if any, Argentines who do not know what the market will support, and will always make the most of the situation. If you come across anyone cheap, they are usually chancers and do not know the market or tango. Those teachers who travel to Europe or the US are not necessaraly the best, just good language skills and freinds abroad.
I would try freind Napoleons class first, my experience of private classes and workshops are that they need to prove that they have something different, and will only cause you confusion.