Odroid H4 family (H4, H4 Plus, H4 Ultra) supports in-band ECC, which supports one-bit error correction and two-bit error detection. And the 8-core model is just $220 (+case, +heatsink/fan, +shipping, but oh well)
It has UEFI and runs mainline Linux, it's an Intel reference design for Alder Lake-N with a couple additions (SATA controller is 3rd party for example)
