Cheap device to practice reverse engineering on?

I want a cheap device which I can practice reading spi flash memory and using ghidra to reverse engineer binaries that live on the firmware. I am wondering if anyone knows of any cheap devices which I can use to reverse engineer and learn. This is going to be my first device which I have actually reverse engineered. I have reverse engineered some openwrt firmware with ghidra but not that much, so I want something that is beginner level.