[jaclaz]

Maybe you don't need a "pen plotter", but rather a "pen robot".

There are quite a few around in the 200-500 US$ range, I'll name a few only as an example to show you what I mean:

https://axidraw.com/

https://uunatek.com/product/idraw/

https://www.banggood.com/EleksMaker-EleksDraw-XY-Plotter-Pen...

https://www.robotics-3d.com/makeblock/3923-speed-plottart-ro...