I remember in 2007, buying my first MacBook. It came with an enormous 2gb of RAM. I asked about upgrading it. The guy leaned in conspiratorially and told me that Apple’s RAM upgrades were a rip-off, and that I’d be better of buying it elsewhere. So I did, for half of what Apple were asking.
This is a grift that Apple have had for far too long, and there’s a part of me that’s convinced that their move to soldered RAM was to stop people upgrading after the fact more than it was about SOC efficiencies.
Linus has made a video about this recently trying to build an equivalent machine. There’s really nothing like the base Mac Mini for its price, but that stops being true as soon as you make any upgrades.