How Much Should You Actually Spend? A Field Guide to the Diminishing-Returns Curve
Every product category has a price above which you're buying refinement rather than capability. Here's roughly where that line falls in twelve of them.
Almost every consumer category has the same shape. Below a floor, products fail at their core job. Above a ceiling, they do the same job with more refinement, better materials, and diminishing practical benefit. The interesting money is in between.
The mistake isn't buying expensive things. It's buying expensive things in categories where the curve flattened two hundred dollars ago, while buying cheap in the categories where it hadn't flattened yet.
Where the curve flattens
Cordless vacuums flatten around $450. Above that you are buying mop attachments, bin compression and displays. The suction stopped improving meaningfully some time ago.
Electric toothbrushes flatten around $60. This is the most extreme curve in consumer hardware. A $60 brush with a good head cleans within a few percent of a $400 one; everything above is coaching and a screen.
Air purifiers flatten around $230. Below it you get inadequate CADR for a real room. Above it you get connectivity and larger coverage you may not need.
Mattresses flatten around $900 for a queen hybrid. Below that, edge support and durability start to suffer in ways that show up in year two.
Headphones flatten around $350. The last fifty dollars of noise cancelling is real, and it is genuinely the smallest improvement per dollar in this list.
Cameras don't flatten in the same way, because the body is a smaller part of the system than the glass. A $1,500 body with a $1,200 lens beats a $2,800 body with a kit zoom for almost every purpose.
The categories where cheap is a false economy
Some categories punish frugality specifically. Standing desks are one: below roughly $300 you get single-motor frames whose keypads fail just outside warranty, and the replacement cost exceeds what you saved.
Portable power stations are another. Below a certain continuous wattage the unit cannot run the thing you bought it for, and capacity is irrelevant if the output is too low to start a compressor.
And robot vacuums, where the gap between navigation systems is the whole product. A bot with no mapping will miss patches forever; no amount of suction fixes a bad path.
How to use this
Work out which side of the curve your category sits on, then spend to the flattening point and stop. In practice this usually means buying mid-range in the categories everyone tells you to splurge on, and mid-range in the categories everyone tells you to save on, which is unsatisfying advice and almost always right.
The exception is anything you use daily for years — a mattress, a desk chair, the headphones you wear eight hours a day. There the curve is the same, but the denominator is enormous, and a hundred dollars amortised over four years of daily use stops being a real number.
