In case somebody is interested: there are decent ST77xx based displays for a lot less than $20 for the 2" size. Otherwise, with $20 you can get a much larger one on AliExpress, always based on the same chip so compatible with the code in this post. If you are ok with paying a bit more and want to be sure to get a quality product, for $20 you can get a solid color display on Pimoroni if you are in the UK or are willing to wait forever for the shipment in Europe.