Not sure if this is the case in the US, but in the EU, you can get a SRAM Rival large chainring for 75-100 euros.
But you can get a crankset for 110 euros. This feels super wasteful, and frankly makes no sense. I ended up getting lucky and getting a crankset for 72 euros. So 3 euros cheaper than just a single chainring.
I’ll try selling the arms for like 30-50 euros but this whole experience has kind of annoyed me. I’ve had similar experiences where replacement pads for a 50 euro helmet cost 30 euros, but that didn’t annoy me as much somehow.
Been the same in the UK for as long as I’ve been riding (30yrs) Its always been more economical to buy a new crankset, swap the rings to my existing cranks and sell the new cranks arms loose on eBay. I don’t know why people buy the loose crankarms, but they always sell! Perhaps they are using cheap chainrings from aliexpress?
So confusing. I can’t imagine this is even an economy of scale thing. The part that’s cheaper contains the part you want to buy. Surely they have to produce the chainring, and then have a human (or machine) assemble it.
Regarding the crank arms, yeah basically that. I’ve done it before where I’ve bought a really cheap set of 2nd hand crank-arms and then put cheap chainrings from Amazon/AliExpress. People also seem to love experimenting with different crank lengths.
Similar with Shimano. I’m not sure it’s literally cheaper to buy a crankset than the chainrings, but they are pretty close in price, and a used crankset might be cheaper. It’s a different story with Campagnolo, but that’s because Campy’s expensive and their rings are about the same price as Shimano.