Their was another thread which discusses paying more for quality.
But I want to ask, when is it ok to just buy the cheapest?
For me its stuff your only going to use maybe once. For example I’ll go to Harbor Freight and buy a cordless drill for $20 if I only want to use it for a couple of days on a project. Better than a $120 Dewalt.
So I’d vote for items your only going to use once.
Most clothing for little kids - paying extra for name brands or double stitching or whatever is kind of silly when they’re gonna outgrow their togs about every 2.4 nanoseconds. (And, if they don’t manage to outgrow them first, most tots will destroy them in creative, sometimes spectacular, ways: permanent markers, grape juice, trying to adopt a baby skunk from the shrubs, etc.)
Most bulk-type foods, like dried beans or rice, and sugar, salt, and the like. It’s the same, whether it’s packaged with a brand name or scooped from a bulk bin or packaged under a store brand name. I can’t tell the difference between the 1.50 box of Morton's salt and the .50 box of Super Saver salt, nor the grocery store cheapie brand of sugar versus Domino or Dixie Crystal.
Apologies for questioning the premise (so early in the thread!) but absolute cheapest, or just cheapest among the choices at a respectable vendor?
I buy the cheapest tires…but I go to a reputable tire store, so I know they aren’t selling utter crap. Just…kinda sorta crap. I could probably go to Tijuana, or a junkyard, or get the cheapest possible…
When Sears has a “Good, Better, Best” lineup of products, I nearly always go for the “Good” – the cheapest of the three.
For clothing, I go to outlet shops and surplus shops, because I really don’t care what kind of shirt I wear. For clothing, I push toward the absolute cheapest. (Any cheaper and I’d be buying fabric and sewing my own.)
The ultimate in “use once and throw away” is food.
If you can stand it.
No more Banquet TV dinners for me, though.
I almost always select the “free shipping” option.
Do you have storage space? If not, then go ahead and buy the cheapest, disposable option.
But mark my words, over the next few months you will find more projects that a cordless drill would be perfect for and you will kick yourself for buying that one that burns out after one or three uses.
Cheap tools or cookware (which are, after all, just kitchen tools), never. Cheap food or beer, maybe. I do buy almost all my clothes at thrift shops though.
For me, airline tickets. Sure, terrible tickets suck. But I’ve never been on a flight that lasted more than 24 hours, and you can put up with anything for a day.
I was gonna say that! I’d rather have extra cash to spend at my destination than use it to get there.
Shaving cream.
You’re small; at 6’4", I’m not. If I can’t guarantee an escape-route seat I have to stump up for a premium-fare seat as often the short seat pitch means I physically cannot fit in a standard cattle-class seat.
Stereo and computer cables.
Remember the Enron(?) guy who bought a $6,000 shower curtain? That was unnecessary.
White rice, sugar, flour, corn starch, and baking soda. I can tell NO difference among the expensive brands and the cheapest brand in the store. I have driven twenty different cars over the last 36 years and have always fueled them with the cheapest gas available. I have NEVER had a fuel-related problem with any car. Paying extra for a brand-name gasoline is just wasting money.
Here’s a thread from a year ago, What do you buy at the dollar store?
Coffee filters, kitchen matches, small tubes of superglue, see above re: use once.
^This. I’ve never understood brand loyalty in gasoline. My other big one is cut flowers. I buy my wife flowers fairly often because she likes them, but I always get the ones on “manager’s special” and rarely pay more than $5 for a nice bouquet - roses included. She knows, and approves!
Once, as a kid, I deliberately took a pair of scissors and cut a hole in my pajamas. Why? Because I wanted to know what cloth looked like at its edge. You usually can’t see the edge of the cloth in your clothing, because it’s folded up into a seam or hem. Oddly, it never occurred to me to just ask my mom, who sews and thus had plenty of cloth with exposed edges already lying around.
Always buy for best value. It’s that simple - although determining “value” can be slippery.
Most of the posts here have the right idea, including the OP. If a less-expensive option does the job and (more importantly) suits you, there’s no reason to buy anything more expensive.
A more formal way to look at value judgment is to make a cold and conservative estimate of how many times (days, instances) you’ll use it before you no longer need it or it wears out. Divide the cost by that number. In the OP’s case, a cordless drill you expect to use for one job and maybe a few more costs either $1 or so per use, or $5-6… but if it’s a tool you’ll use indefinitely, once or twice a week, the better one will last much longer, do a better job and cost only a few cents per use over that time. Well worth the extra cost - and you can’t minimize convenience and comfort over longer use or ownership periods as inconsequential. More power, a better grip, dual batteries, a faster charger… all of these will add up for an oft-used tool but could be dispensed with for something used only a few times.
The factor is called RCU - Real Cost per Use. It can get frightening and/or instructive when applied to things like motor homes, power sports equipment, high-end clothing and the like. 
Sorry to be a naysayer…
The end result using your flour will taste the same, but I’ve found the quality of flour affects the texture and rising qualities. For example, I know I will always get a great loaf of bread that rises exactly this much in this amount of time when I use King Arthur Flour. Use the store brand and it’s a crap shoot - might take a whole hour for the dough to rise and even then the texture won’t be that great. This is because of the quality control testing in concerns to the amount of protein in the flour - King Arthur tests a lot and gets the same percentage every time. Store brand just sources from wherever and the percentage is all over the place.
White rice, the only difference you can tell is in freshness. Considering that the majority of rice is shipped in from overseas, we’re not really going to get much of a chance to taste rice that’s a week out of the paddy. So there’s a difference to be had…just not in the states.
I avoid certain gas stations because the fuel at those stations has more sediment (or something) that causes my car to “hiccup” every now and then. It’s less a brand thing than that certain stations have shitty storage tanks.
Mrs. B. is the baker in the family, and long ago went to mail-order yeast and King Arthur or Red Mill flours for just those reasons.
Oh, and we order extra gluten, too, which amuses me no end. 