On amazon there's still the occassional evga 1080ti sc2 for $830 and some MSI/Zotac models below $800, but they sell out in a minute.
Must be fast!
Yeah..
Not only on Amazon, also another online store very faster sold out if price normal or cheaper from another seller.
R9 390 ( 34 mh/s but nearly 300w )
At 2017, I buy secondhand R9 390 8 GB priced $170 on the Online store. The shortcomings of this GPU is heat and the hungry power consumption except someone have doesn't problem in electricity (cheap or free).