You can try to look for a used X79, I have decent experience buying a used Lenovo S30 workstations (you need to be careful about the exact model number though, because some of them only support Sandy Bridge / v1 CPUs)
Alternatively, there are some brand new Chinese X79 boards available on ebay/aliexpress priced around $100 which you can take a look at
You are going to want an X79 motherboard. They are old enough that you should probably look at used. An example -- https://www.asus.com/us/Motherboards/X79DELUXE/overview/
You can try to look for a used X79, I have decent experience buying a used Lenovo S30 workstations (you need to be careful about the exact model number though, because some of them only support Sandy Bridge / v1 CPUs)
Alternatively, there are some brand new Chinese X79 boards available on ebay/aliexpress priced around $100 which you can take a look at