As much as I would never want to see any of those presentation slides or spreadsheets with all the reasons why you are doing as well as can be expected, I would still expect you to be able to put such things together in some sort of reasonable business argument. But I suspect that it's not your 'gut' telling you that everything is fine, that's ignorance. I certainly understand the perils upper management meddling in affairs of which they know nothing, but I also understand middle management resting on their laurels and thinking they're doing 'just fine' without any way to try and judge that metric.
Getting a baseline on what similar departments might be spending can sometimes be helpful. But your goal shouldn't just be to find some metrics by which you compare favorably to the competition and judge that everything is fine. Every time you have to sign off on a purchase order for new hardware or renew a license for software you should be asking questions about value. Change by itself is never without risks, so the mere disruption of existing workflows might be reason enough not to switch to some alternative, even what that alternative is 'clearly' better.
You should be able to make your case for all your spending, such as why it's needed and why it's the best choice for your business. It doesn't always boil down to easy numbers for the bean counters, but at least be able to put on a good show.