Not sure why you consider cup and cone designs "dubious". The technology is proven and inexpensive to manufacture; it does require manual tension adjustment and periodic overhauls. To me, the last is actually an advantage, because I know that all I will have to source is new standard ball bearings and a decent grease, and I'll be good to go. With cartridge bearings, it's my impression that the bearings aren't standardized, and you might easily end up without a bearing source at overhaul time.

My few-year-old Giant Yukon came with wheels that had decent WTB rims and stainless spokes, but Formula hubs. When the rear hub failed after about 1000 miles, I was pretty disappointed to find out that the cheap Formula hub couldn't be rebuilt because it had cheap pressed-in bearings, so I had to throw the wheel away and get a decent new one built with an XT rear hub. Some people may wear out the rims first with rim brakes, so hub longevity might not matter so much to them, but I've got disc brakes and would like to keep my wheels for 1000s of miles.

In my area, there are shops that also sell used components. Since it sounds like you're very price-sensitive on this build, why not see if you can pick up a pair of still-good Deore or better used rim-brake hubs? Overhauling them with all new ball bearings shouldn't cost very much. At my favorite local shop, you can pick up a decent used Shimano rim brake hub for $5-15.