I think it really comes to running a comprehensive analysis of what you spend money on throughout the year. Calculate everything you spend money on annually. Factor in costs. See what money you're left over with. Add in some investing goals. Then factor that in and see where you end up with. At the end, if you have money left over and you don't feel it needs to be added to savings, and you're satisfied with your current investing (retirement/extra, etc.) THEN by all means, blow the money on cool shit. Because at that point you've done your due diligence and have a clear understanding of whether a certain purchase makes financial sense and is worth the tradeoff you get for having that thing.
Of course there is always opportunity cost. I.e. "how much could I have made by investing that money in something", however this needs to be balanced with your long term goals and how much satisfaction you'll get out of buying the thing you want.