Do you know what code your getting? (autozone will scan for free) The traction control light is nothing to worry about usually. It just comes on with the check engine light, its toyotas way of saying, "hey fix this" rockauto.com and oxygensensors.com sell the o2 sensors for a good price, and they're not hard to change usually.
My local mechanic told me it was the P1035 I think code. Something related to heater air flow bank 1 sensor 1. I've been looking around, and it seems pretty expensive. Almost $200 or so. I also have a $75 Lexus Dealer gift card from their card services, so my assumption would be that labor would be free for and I'd just pay for the part. What do you guys think?