A few differences on the market right now you could argue if you went bottom billing:
- $160 = 32GB DDR4 RAM (-$40)
- $65 = 240GB SSD (-$35)
- $50 = 2TB HDD (-$30)
- $15 = DVD-RW (-$25)
- $75 = PSU ($-25)
- Total = -$155
$70 for the case, $100 for the motherboard, and $40 for the KB+M combo all also seem a touch high, but they might not be, and it's impossible for me to presume. I find it highly unlikely that you could save more than $50 from what he has allotted above on all three combined. So I could see myself down-valuing his appraisal to $1825 with all of that. Nevertheless, the cost of liquid cooling has been overlooked. That will add ~$50 back at least.
I'd say just about any way you slice it this is a $1,900+ machine on raw parts & OS software alone. One could quibble about overkill for a gamer build with the RAM and the "Pro" licensing, but it's not like downgrading those makes up the ~$275+ advantage over the market price, so why fret that you cannot downgrade?