I consider Sao Paulo to be the most expensive Brazilian city, but with these tips in mind, you can visit Sao Paulo without draining your bank account.
Budget transport tips
For your movements around the city, use the metro and get a Bilhete Unico ( metro card). This way you spend less than $5 on transport per day.
On Sundays, you can consider renting a bike as the streets are usually not crowded.
Meal budget tips
Get your meals at Mercado municipal square and Liberdade neighborhood market. There are restaurants offering Brazilian and international cuisine for less than $20.
Tours budget tips
Visit places where entry is free or costs less than $30 at most. These include
Ibirapuera park- entry is free
Sao Paulo art museum- entry is BRL 15. One of the largest and cheapest flea markets is outside the museum every Sunday.