First ever custom loop. Really love how it turned out.
Total cost of the "essential" water cooling parts was around £300/$380 due to scouring second hand for about 6 months prior to building and finding good things on AliExpress.

Radiators and CPU block were second hand, with everything else coming from AliExpress primarily from bykski and barrow, and coolant from XSPC

Added the EK GPU backplate for £40 because I love the mirror finish.

Full Spec description:

Watercooling Parts:
Bykski Titan X Pascal GPU block
EK Evo AMD RGB CPU block
Two 360mm 30mm Magicool Rads
generic PWM pump (from aliexpress)
Barrow 14mm chrome fittings and 14mm PETG tubing
Top fans are just general NZXT fans I had lying around, RGB ones are from Aigo (decent enough but could be better)

Components:

EVGA 1080ti SC at 2050mhz Core and 6250mhz Mem
Ryzen 5 1600 at 3.95Ghz
16GB 3000mhz Corsair vengeance pro RGB
Gigabyte X370 Gaming K7 motherboard
PC-o11 Dynamic

GPU doesn't go above 45 at full load gaming.