What's the maximum resolution I could get using these monitors in a Tri-Monitor setup?

[stun2record]

Middle/Main Monitor - http://www.amazon.com/gp/product/B00B2HH7G0/ref=ox_sc_sfl_title_1?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

Side Monitors (2) - http://www.amazon.com/gp/product/B00ANKMNXO/ref=ox_sc_act_title_2?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

I was thinking 5760x1080

 

[geofelt]

Since all 3 monitors have a 1920 x 1080 resolution, I see no reason why you could not get your desired 5760 x 1080 resolution. But, because the side monitors are slightly smaller your images will not match up. T there will be color differences as you move windows from one to the other.
Do not chase that 144hz refresh rate. It is unlikely that you have a graphics configuration that will drive 5760 x 1080 at a sufficiently high FPS. I think you would do better with your budget to buy three identical monitors, preferably IPS ones with wide (178/178) viewing angles.