Are you looking for a school in particular or just a teacher? Because there are heaps of teachers offering lessons on Craigslist that are lots cheaper than schools, generally they give lessons at their houses or in a park or coffee shop. I used to take lessons with a teacher I found on there and she was really good.
I and many others on this forum have had similar experiences with Spanish language schools…namely, that they are expensive and waste a lot of your time with other students who are slow learners, slackers, partiers (and show up late and hungover) and lengthy coffee breaks. I did a week in a school downtown, and after spending the equivalent of about $10 per hour (back in 2009) to go for 20 hours per week and get about 4 hours out of it, I found a private tutor and she was 100 times better (and cheaper). I went three times a week for two hours and it completely transformed my ability to understand and speak Spanish. There are many recommendations for schools and teachers here, but I know a number of people have also recommended Adriana Crom, who was my instructor. She teaches out of her quiet apartment in Recoleta, and she never wastes your time. She speaks perfect English as well, which really helped me to learn the rules of Spanish grammar.
Adriana's contact info is:
Went to UBA. Waste of time. Teachers didn't show up/showed up late or sent replacements who had no idea what the other teacher had been teaching.
There were times (and this is a beginner's class) where they told us to tell them about us or explain the context of a passage we just read or whatever from the workbook and they gave us 30 seconds on the clock to do it. Putting that kinda pressure on me doesn't help me learn the damn language, maybe you're different.
Go with a private tutor. That's probably the best advice you're going to get.
I enjoyed the UBA course I took (nivel 5), although the class size was larger than expected (15) and several times the professors were > 20 mins late. But way better than the group classes I took from one of the Palermo schools; the UBA professors are actual professors - I learned a ton.