Ask HN: How do you decide whether you buy something or not?

I try to do what I can, where I am, with what I have. It's insane all you can accomplish with a laptop and a bit of hard work.

Basically items bubble up to the surface given enough time. There's times when certain things just must be bought (if it's important enough). I let it happen naturally rather than force it.

Basically it’s all in the title. Nevertheless here’re some thoughts in advance. There are things constantly on our mind that we think we need or things we wish we had. This may be something to boost productivity, get in shape, that makes us feel good or maybe more essential reasons. But there is a catch. We don’t know if these things make us do or feel, like we expect them to do. We don’t know if we actually need them. It’s hard to think rationally about things we personally expect something from. Into the bargain, there are marketing agencies whose solely job is obscure our mind and make us think we disire or even need something (which we don’t). Given, you are not in the situation to buy it all and try it out, how do you decide whether you buy something or not? Any strategies, thoughts, questinos, anything to help make a more rational decision?