If you want the best scenario of an all-in-one unit (available today), get a Toshiba Tecra M7 (either factory refurb’d or a gently used one from eBay - but make sure it has the Nvidia GPU) - it’s a 14.1" Wacom screen flip tablet and had a speedy processor. We have a few of them in the studio. They run Sketchbook Pro, Rhino, SW, Adobe Suite, Office, etc with no issues, but the best feature is that the screen is great for sketching, it has the least feeling of ‘disconnectedness’ of the flip screen laptops and was the largest of the group (Fujitsu, Dell and Gateway made competing units but they didn’t have the Nvidia GPUs and I never felt their screens were as good as the Toshiba’s).
I’d bet you could pick up a Tecra M7 for $300-500.