Intel Core i7-9700K Processor $495.20 | Core i7-9700 Processor $439.20 | Core i9-9900KF $639.20 Delivered @ FTC Computers eBay
Also the cheapest current generation 8-Core i7 is also available for $423.40: i7-9700F but only 2 remaining. Keep in mind that this one does not come with the integrated intel graphics (needs dedicated graphics card)
Some people have had trouble with FTC computers over long delivery times so keep that in mind. I ordered a CPU last time from them and it arrived quickly though.