Oh aye, dealing with perishables is easily one of the more sketchy bits about home cooking. There's various fancy ways to go about mitigating it (drying, canning, etc., etc.), but personally I mostly just don't cook much with stuff that goes bad quickly, heh. Beyond that it's just figuring out what you(r household) will actually use and tailor purchase habits to it. Do indeed often have to pay more if you're going to avoid wastage, but *shrugs* Regardless it's going to cost less than the alternatives, by and large.
E: Though the other thing to do is make that one thing in bulk, but make sure it's something you can add to pretty easily. There comes a point you can't eat any more lasagna, but that point stretches a lot further if each one has different spices added in when you re-heat. Maybe one has extra cheese, one added peppers or something, another worked into a quick soup base of some sort (can be tricky with stuff like lasagna, but if you have a fairly thick base, via adding something like mashed potatoes or rice or whatever, it can work out well enough), stuff like that. I drive some of my family a bit up the wall by largely eating the same things regularly, but the trick is for all I'm still cooking noodles or whatever, wht I do to it changes. One type of sauce one day, cheese the next, bacon bits the third and so on.