It is good to be frugal, to as it were, count your pennies. But the old axiom not to be "penny wise and pound foolish" holds true and should be heeded. A note here...this is not a mixed metaphor but a British saying in reference to the pound which is also a monetary amount.
Think post-its, peaches and paints.
It is penny wise and pound foolish to buy post-its in any brand other than the original, and those should be the extra sticky ones. Why? Because anything less just does not stick, at least not in my experience, so you're just wasting your money. The post-its end up in places you don't want them because they won't stay put.
Generic canned peaches are o.k. in a peach cobbler that will be baked to a very soft state, but if the peaches are going to be used in a gelatin or such you'd better spend the extra money on the brand name because the generic ones are generally hard.
House paint: buy the best you can afford. Why? If you pay someone to paint your house the greatest expense you will incur is the cost of their labor. A good quality exterior house paint properly applied will last for years, whereas cheap paint will likely be peeling in 3-5 years, necessitating repainting and the huge expense of paying someone to do it all over again. And even if you don't pay someone, but do the painting yourself, do you really want to do it all over again in a short time? I know I wouldn't. Money spent on quality house paint is money well spent.
Keep the penny wise pound foolish axiom in mind next time you make a purchase. By spending more you may be spending less in the long run.