Probably my iPad. I say that because it's too expensive to have it replaced if something happens to it. I have actually had my screen replaced by this guy at the mall because it was severely cracked. It cost over a 100 dollars to fix it too. The second most expensive thing is either my PS Vita or my 3DS. Though, I can easily replace my 3DS with another one if something happens to it. I've dropped that thing so many times that I'm surprised it still works. We have a tile floor so...
Oh, and my old Mac laptop. Laptops are very expensive, and this one I'm using is my mom's old one. It functions really well, but I can't download most apps because of the software not being updated. My parents couldn't afford to buy me a new one. Plus, there was nothing wrong with this one, so I got it and decided to use it in place of my crappy HP laptop after it got filled up. My HP laptop was used, and I think the person who had it loaded it with things that shouldn't be on it. It was weird because no matter how many times I tried to defrag it or delete unneeded programs, it wouldn't even touch the memory. D: