Mac Studio with M5 Ultra Now Available with 512GB RAM for $22,299
macrumors.com
macrumors.com
Apple charge £4000 to go from 96GB to 256GB, and then an extra £11,500 to go from 256GB to 512GB. There's "Apple tax" on memory, and then there's this. £11,500 is pretty much the cost of another high-end Mac Studio with 256GB of RAM in it!
So I guess even though I'd considered getting a 512GB machine, that's not happening now.