Aeromexico has round-trip flights from Dallas (DFW) to Sao Paulo (GRU) starting at $418 with a connection. Availability is sparse and scattered from February to March. Mostly midweek. 5-day minimum stay required. Visa required.
Note: Carry-on bag is allowed for free, but checked bags will have a fee. Upgrades into “Regular Economy” available for +$25 each-way.
Note: Stick closely to the example dates provided, other dates seem to have long connection times.