Same here. That's why I tried to reduce my spending last year, and did it with reasonable success, even though I still bought tons of games. Unfortunately I discovered Steam Gifts and since I enjoy giving away stuff this adds an incentive to buy more games. If I don't play them I can always give them away.
As for Plants vs. Zombies, I have both the PC and Android versions and I played it more on my phone, because it's a more accessible device and the game is really suited to touch control. So I'd recommend going with that version of the game (which costs $3) if you have a suitable device.