2011 was the last good year for Apple products that are repair/upgradeable, atleast for computers. When people ask if they should buy a new iMac to build games with Unity I always tell them to get a cheap 2011-2012 MacMini and upgrade the ram and disk. But thats a 7 year old device, you're stuck with a dataed CPU (which can get the job done,) but def not my every day.
If you want to get a desktop device and save on hardware, the best option these days is probably to go Hackintosh (though I've read it can sometimes be a bit annoying to upgrade the OS). iMacs generally are surprisingly good value though.
Hackintosh user for 4? years there. Stick to verified specs and you'll be fine. Haven't had any problems since setting everything up. Although I do keep hot backups just-in-case... But I'd do that using OEM iMac too, so not much of a disadvantage.
