Xeon E5-2697v3...
The Xeon E5-2697 v3 is the budget option I tested because of its higher all-core turbo, and it’s a solid value if you’re trying to keep costs down. Even though it boosts higher under load, in my plotting runs it came in around 26 minutes per plot, so you’re trading some speed for savings.
You'll be taken to Ebay to complete your purchase.