worth the money

So, I've got a 2002 Mazda Protege5 that's practically all stock. I've asked around to see where I should start upgrading it, and a lot of people have said a cold air intake is a good place to start. After some looking at the differences between CAI's and short ram intakes I found a short ram...

I've seen a Mazda 3 diesel '04 reg for sale, it's currently for sale on eBay for 466 bids going up, tell me whether you would buy it as an investment. Here is the description; CAR DETAILS We have for sale a 2004 04 Reg Mazda 3 TS Diesel Sold with 1 remote key, V5 Registration document Mot...