* I got my AxiDraw as an impulse buy for a Black Friday sale. They go on sale around then
* Search AliExpress for "AxiDraw". There are cheap clones for ~$130 shipped
* Thingiverse/etc have some DIY plotters in various form factors: Stationary like an AxiDraw, polargraph (hanging from two points vertically), little plotter vehicles that "feed" a paper through by rolling over it...
* Old 1970s/80s retail plotters (i.e. HP). These are sometimes more trouble than they're worth, both mechanically for repairs and software-wise. Serial port versions are more rare than HP-IB versions. The drawingbots Discord has good vintage info here
As someone who bought a ~$150 knockoff plotter, I wouldn't recommend them unless you're unsure and just dipping your toe into the hobby. The plot quality will suffer -- even small amounts of backlash or slop in the mechanism and pen carriage will result in irritating and unfixable offsets in finer detailed plots. The bigger issue is actually software support -- all the hobbyists shell out for the Axidraw, so it's the only well-supported unit on both an art-software-workflow side and plotter-driver-software side.
Find an old flatbed HPGL-compatible one, from ~1985-2000. You may have to wait for one to show up near you, you may need a USB to serial (DB9) adapter [1], and you may have to jury-rig a pen holder if official pens are no longer available, but the cost will be a few 10s of dollars. Look for one with manuals and pens if possible. Graphtec, Roland, and HP are good brands.
Plotters are really fun, and HPGL is easy to generate with code.
[1] Or get a thin client with a serial port (I have an HP t630) and put Linux on it and use it as a plot server.
You could also go down the DIY route and build one yourself. I did just that and am really happy with the outcome. Check out https://ben.akrin.com/plottybot for a great design and instructions
It's pretty crazy if it's just to generate some pictures for fun, especially when there are alternatives. I have an A3 flatbed Graphtec plotter with a precision of 0.01mm [1] that I got for something like NZD$40 (>20 years old, but perfect condition).
[1] Not a typo, but I don't have a way to check it. I use it in its "low accuracy" 0.025mm mode.
I bought a Vigotech VG-X4 and did get it to work.It was around 200 dollars.
However there were a few issues - bit fiddly to construct (the same might be true of the axidraw i guess) and windows only. Found some software online to drive it on linux.
There's software to use pens on a 3d printer to draw on paper on the bed, and it wouldn't need to be a very high specification on to turn out acceptable results
