I feel bad enough shelling out close to $30K (with taxes and fees and BS) for my new Camry. It would be easy to spend thousands more on mods, but I try to remind myself how silly it would be if I did. Why not just get a better car in the first place? This question always reigns me in from spending big bucks.
That said, I've spent about $400 in car-care products (orbital polisher, waxes, sealants, cleaning stuff, etc.), $500 for VentureShield, and $200 for my XenonDepot HIDs (which still don't work properly yet

). If I had to look into a crystal ball and guess my future expenses, I might:
1. Upgrade the rims when I need new tires ~$1000
2. Get an intake/exhaust when my warranty expires (don't want to hear any BS from the dealer or Toyota if I run into a problem; tranny is already on the fritz at less than 4K miles) ~$500
3. Get "proper" HIDs ~$450
-G