This mod can be purchased unranked from the Void Trader Baro Ki'Teer for 200,000
200,000 and 280
280. Note, however, that Baro Ki'Teer's stock changes with each visit, and he may not have this item available next time he appears.
Primed Slip Magazine is essentially the Slip Magazine mod with Legendary rarity and 5 more ranks. It is considered the same mod as its Common counterpart, and thus both mods cannot be equipped together.