This NT only armor is one of most expensive sets out there. Like usual, reason behind this doesn't lay in benefits it brings, but in the problem of obtaining parts. The main building component is Notum Saturated Metaplast Shell, which to my knowledge drops from only 3 sources. The lower QL ones can be obtained from small underground robotic mobs, usually referred to as Moles (also go by the names of Shovelet, Diglet, Scooplet) and are found in Aegean, Pleasant Meadows and Broken Shores. They drop ql 40 to 90 shells, but the droprate is less than 0,1%. Second type of mob that drop ql 140 to 200 Shells are Hollow Island Brood Champions. Beside being raid mobs, those too don't have good droprate either, but at least it's still better than Mole's. The third source of shells is from the Collector. While demand for shells is low, poor droprate makes prices exceed 10 million at times (usually it's lower).
Beside 7 Shells (if you aim for full suit), you'll also need following :