486Tang - 486 on a credit-card-sized FPGA board

The Sipeed Tang 138K FPGA hosted by a retro console-style breakout board is available for around $120, or a bit more if one wants a fancy case.

This Verilog implementation lacks an FPU and the '386 chip's virtual '86 mode, but might be of interest to operating system developers who want to get further into the chip than is normally possible without expensive (and these days unavailable) ICE hardware.