This post got me to purchase an Axidraw back in 2017 and I had a ton of fun using it to plot neural data I collected during my PhD, as well as messing around with generative art. So much more worthwhile than I expected for an impulse purchase.
Also the ender series of 3d printers can make use of a pen attachment as well, but those are 8x8 inches. There are larger 3d printers, and the software or whatever to plot with the ender 3 was open source enough. My ender3 was <$200
generally, though, i do enjoy taking advantage of scaled-up (cheap) commercial products. but i also value supporting an open, small business (EMSL, and now Bantam Tools) that is active in the communities using its products.
You're really paying for the dedicated use-case design (the pen carriage precision on the Axidraw is excellent) and the active software support both from the company and the community.