I did something similar but not so extreme at HD 2 days ago. Bought some wire by the foot. At ~4x the price of per foot versus a full reel. I bought the equivalent of 1/4th of a reel for 1/2 the cost of a full reel. And didn’t even get the reel!?!
If they’d had a full unopened reel I’d have bought that just on principal even though I’d probably never use much more of it. But of course although their computer said they had a couple more whole reels in stock, neither I nor the surprisingly capable clerk could find them.
I bought a string trimmer for my beach house last fall from Home Depot. I was getting a battery one. The same brand as my other battery tools because the batteries cost almost as much as the tool. The trimmer required two batteries. As usual, they had tool only and tool plus batteries and charger. The one with the batteries was $50 less than without batteries. I assumed they were improperly priced. Nope. With batteries was cheaper than without.
I sometimes do that, and take the leftover parts to our local Habitat for Humanity Restore store. Turns out that lots of others donate spares too, so sometimes it’s worth it to check Restore out to see if they have the parts you need.