The entire headlight assembly
The entire headlight assembly is horrible. I have a 2004 with 255k miles on it. Toyota wanted to charge me $400 when my headlight went out. Pep boys said $200. Thankfully my husband looked online and found a YouTube video, and changed it after we found a HID headlight in sale for $70 or so.
Only issue? There is so little space in there he sliced open the back of his hand and still bears a scar 10 years later. So now it's my job with my smaller hands. Still it's been a really reliable car.
Oh, and the rear view mirror assembly cost is appalling too. I need to find to cheap black ones some day...