Start with radiator.
Should cost about $80 if you take it out and give it to a radiator shop.
New thermostat is about $16
Get Toyota genuine on this.
Flush the block with the garden hose while the radiator/thermostat is out.
Put it all back together and refil with Toyota Red.
If it still overheats, get a new waterpump.
After this if it still overheats while driving, BHG is a lot more probable.
If it overheats while idling in traffic, the viscous coupling on the fan is dying. Get a replacement from a wreck.
If it still overheats, BHG is a lot lot more probable.