It features ofc. like what tim has say that 1080p TN cost about $500 but u must know that it comes with a higher refresh rates like 144hz (though there are some 120hz at that price point as well.) and many other features as well, which means it isn't using the standard IC and beside that the panel that use also modified from been a standard 60hz as well.
Therefore for monitor like this acer, with G-sync, 1440p, 165hz and ips panel, it already consider price oriented monitor esp for FPS gamers. (but ofc the impt is still the input lag even though it has 165hz, but there are many factors as well.)
even if u find that price isn't worth that much den go for others where some features are less better, but what u get is still the standard monitor.
$600 vs $1k does proof to be a deciding factors on the prices, but u are not comparing apple to apple, u are apple to orange on the overall scale.
anyway the prices point factors is the the panel and the fast refresh rates and the IC that causes it be more ex. and if u find that its ex, den go with a standard monitor that fits your budget/needs. but if have a high budget why not get this monitor to enjoy it ?