Actually DF looks at this.
We ran the game on our recently constructed "next-gen" Digital Foundry PC, pairing a six-core AMD FX-6300 with a GeForce GTX 760. Texture quality needs to drop to very high, but otherwise, everything is on max and we can hit 1080p60 with lashings of anti-aliasing, but the performance level is not sustained - but still a clearly noticeable improvement over Xbox One."
I can't speak to the exact cost of that testbed, but an FX-6300 is around $129. A GTX 760 is maybe $280. You can build the whole system, I'm guessing, for $600 - $650.