Most of the 360s (AIO's) are over 100 to be honest but to be fair custom loops aren't any cheaper and are far more hassle. I think I've decided to just sell of whatever WC gear I've got and put that toward the cost of the aio
I'd say my loops have been pretty hassle free. My first WC loop consisted of:-
EK Supremacy Evo TR4 (from OCUK)
EK X-RES 140 Revo D5 PWM (from OCUK)
EK ZMT 3/8" 5/8" (from OCUK)
Barrow fittings
2x Magicool 360 G2 Slim (from OCUK)
MSI GTX 1080 Seahawk EK X
The loop used distilled water with ~20% mix of Mayhems XT-1 clear concentrate. It was put together ~Q3 17, Q4 I changed the GTX 1080 to RX Vega 64 with EK-FC Radeon Vega (copper/plexi); drained coolant looked clean & clear I reused it. ~Q1 18 I changed the CPU block for Bykski A-Ryzen-ThV2-X, drained coolant looked clean & clear I reused it. Loop was left as is for a while, then ~Q4 19 I tried 2x TR2920X. These CPU changes did require loop drain and block disconnection. Due to how TR socket mechanism is, size of it and CPU, the length of flexible tubing/room for movement did not allow CPU changes with ease unless disconnected block. The loop was then reused on an AM4 setup, here I can change CPUs without draining, feels like an AIO.
I'm still on initial coolant filled back in Q3 2017. Dunno if I've been lucky with it, dunno if it was because I cleaned blocks/rads/tubing/fittings well prior to loop being put together.
2nd loop system I didn't need up and running ASAP, some savy buying (some new/used parts) pretty much made it half the price it should have been. I used to be one for using large high end air coolers, much prefer the WC route now. Yeah buying in can be higher, AIO I don't even consider as I think WC is much more versatile.