I found this great blog post over at the Minimalist Mom that really spoke to me. We really are bombarded by a ton of ads within a given day thus causing us to want more "stuff." But is the "stuff" what makes us happy? I'd be willing to argue that it's not.
In addition to the suggestions she mentions to tame the Want Monster, I know I evaluate my purchases based on whether or not I can justify long term use of an object. If I'm only going to use it for a short bit of time, it's probably not worth spending money on. There must be an alternative. I also don't make impulse purchases. I always give myself a few days (sometimes weeks or months) before I buy something. I like to really think about whether I need it or not. Most of the time, I find out that I don't need something and thus I avoid spending money on it period.