at what price point do wheels plateau and differences in aero/ride/etc become so small its negligible?
No one really knows. A lot of the info that gets out to the masses is marketing BS.
But if you buy Zipp 303 or 404, you don't need to pay more to get more. The same goes for Reynolds, Knight, Campagnolo and a lot of other brands. Some think that chinese carbon rims are inferior to the name brands. I disagree. My chinese ones are very good, and considerably more affordable.
Just pic the ones amongst the name brands that look coolest. Seriously, I think that would give you the biggest satisfaction.
IMO there's fundamentally three tiers of carbon wheels:
1. Brand name stuff well over $2k-$3k+
2. Small company stuff that owns/designs their own molds but still ship them from China/Taiwan, usually $1k-$1.5k
3. Out-and-out no name chinese carbon from open molds, $400-$800 (sometimes they will be rebranded and sold as #2 tier)
How I see it, the most reasonable/cost-effective approach to this (may vary based on your income
) is to reserve #1 for race day/special occasion, #2 on your posh sunny day bike, and #3 can be swapped or used as often as your aluminum wheels on your every day commute, given that you've done your research and are confident in them. I have personally put a $400 set of chinese carbon (38mm "ICAN") through a rainy Seattle summer/fall/winter/spring 5 to 6 days a week over 13,000km and they were just fine for me (the brake track went shiny/smooth by the end).
Multebear recognizes that riding your bike for most people is for enjoyment, yet fails to to see how running light, deep dishes is far more enjoyable than heavy aluminum that makes your nice steed feel like driving a bus. Does the performance benefit matter when you're just on a ride to work or going for a Sunday ride? Probably not, but it feels good to go faster. The flipside is to only ride downtube-shifting steel every day and only ride your pride and joy bike in competition..