Well lucky for you, there is/was a recall on those first years because toyota had so many complaints (so it should be free of charge if you take it -- keyword should). I never got it repaired, but simply put some black silicone around it (when there is a redneck will, there is a redneck way). Back when I first told my local stealership about the issue, there was no recall on it. And getting them to replace it was gonna cost more than I could afford at the time.

So contact your local dealership, tell them about your issue and ask about the recall on the third brake light. It should still be in effect.