You could use an older AMD Zen CPU with a consumer motherboard that has ECC support. Gigabyte and Asrock are manufacturers I know that list ECC support on their

You could use an older AMD Zen CPU with a consumer motherboard that has ECC support. Gigabyte and Asrock are manufacturers I know that list ECC support on their product pages. The ECC memory is going to eat up most of the budget I would say. Make sure you don't buy Registered ECC memory under this plan.