If you are not using the gpio you should look at mini PCs instead. More expandable and runs x86 processors, not to mention abundant on second hand markets.
Even if you do need GPIO, Arduinos and similar microcontrollers have avoided the price insanity plaguing things that use discrete RAM, so just buy a cheap microcontroller and use it for GPIO paired with an old PC or mini PC.
If you are not using the gpio you should look at mini PCs instead. More expandable and runs x86 processors, not to mention abundant on second hand markets.
Even if you do need GPIO, Arduinos and similar microcontrollers have avoided the price insanity plaguing things that use discrete RAM, so just buy a cheap microcontroller and use it for GPIO paired with an old PC or mini PC.