I think this is starting to drift off the original topic, but I too am always amazed at the amount of gear I see here, ebay, and elsewhere being sold new and unused.
Often it's "I had a trip planned, it fell through," or maybe you lost the tags, or kept it too long; often it's just plain 'addiction' for lack of a better word. Right now I'm talking myself into returning a ULA Ohm. I ordered it and the GG Gorilla. In an close call, I went with the Gorilla. There's no reason to keep the Ohm, because it fills exactly the same niche. But I want to, really badly, because it's just a fine piece of workmanship. I tell myself I'll switch off packs, and the Ohm *does* have more volume, etc, but I know in 3-4 months, I'll be looking at something that I really could use, (winter tarp, say) and then my credit card bill, and then in the closet at the Ohm (used once or twice), and I'll end up selling the Ohm at a loss just to get some money back.
But I find my biggest downfall is, as Ben said, 'the sale.' I know exactly what piece of gear I want, but then I see something on gear swap, or ebay, or 40% off, and it's close to what I want, but not exactly, but the deal's so good, I *have* to get it. In the end Though, I still want what I originally wanted, not a cheaper approximation. So now I'm trying to keep myself from buying deals, and instead just spending the extra money on exactly what I want, which ends up being cheaper in the long run.
I bought cheap sports authority/campmor/walmart gear for years. Maybe setting yourself a low budget and trying to meet might be a fun challenge, but in the end more expensive, quality gear is just a better overall deal. Not only will it last longer, it's really not *that* much more expensive, and if you buy from a cottage gear maker, you're not contributing to a sweatshop. owner.
It's funny because part of the UL philosophy is the keep it minimal and light on the trail, but then at home our closets are anything but minimal. In the end, it's just knowing when to say when.