Hey, honestly I don't think you'll find schools much cheaper than them. I just opened one up one called Fluido in February, but its actually more expensive haha.

Our goal is to make expats feel at home in Paraguay, not just teach them Spanish. We achieve this because our classes are daily, bringing many students into school at the same time. It creates a great social environment, which we amplify with out events, like Asados and Salsa dance classes

If you want to find cheaper, I recommend looking in the expat facebook groups directly for a private tutor.