First off, this is a great site. I've owned a 1988 BMW 635csi and there are some excellent sites like this one devoted to that car. My "new' Prius has 140k miles on it but looks new - save for 1-2 slight dings. The cost was $7,000. The seats and interior also looked new with the only blemishes being some water spots behind the instrument panel and a burned out HID bulb. I bought a pair of bulbs on Ebay, a headlight fixture, and the control module. I probably didn't need the fixture, which was over $200.00. A pair of bulbs was $25.00 and the module was $50.00. As many others have said, the dealer wants big bucks for parts and installation of the lights, but there's several great videos on youtube that explain everything. I changed the oil (Mobile 1) and filter (Toyota) first. Next, I'm lining up parts for future jobs that will probably be needed. There was no maintenance history with the car, as is typical with used car dealers. I have a new set of Iridium plugs and coils ready for installation. I'm shopping for Brake parts (Toyota brand) and have located a nearby experienced Prius mechanic - I've done a lot of brake jobs on previous cars, but prefer to spend money and someone else do them on the Prius - plus I hate working on drum brakes. I'm also shopping for some suspension upgrades - I'll probably opt for a brand like KYB or Bilstein for these. Would love a set of light-weight wheels but that can wait - that's about the only pricey cosmetic item. Have also sourced suppliers for both batteries. I'm loving the car. At first I missed the acceleration and speed factors but now find myself driving with less stress. I should have bought one of these years ago!
I'd suggest you don't go too mad changing out everything yet. Get the feel of the car and make sure there's nothing major that's wrong with it before throwing a lot of money at it. You can register on the Toyota website "owners" portal, put in your VIN number and it may show some of the repair history. Most of the hybrid related parts are warrantied until 150k miles, so don't go out paying for a new hv battery when it fails.