Hi, crazy to buy everything (new) from scratch. Currently, i run 5 machines as well. But beside my main, the four others are cheap and were bought used. But the general setup (regarding monitors) i do have similar as you planned it. So a 32" 4k for my main in front of me plus my healer on the left on a single 24" plus the 3 DPS (with HDMI split view) on an other 24" monitor on the right side.

So good luck with you bild. Do you have any plans how to wire-up the controlling (attack/movement etc) of your chars?