Mandalorian Enforcer Armor Set

The Mandalorian Enforcer armor set can be purchased for 3,500 Tech Fragments + 500,000 credits per piece from the cosmetic Tech Fragment vendors in the supplies section of the Fleet, as of update 7.0. This set is wearable by characters on either faction at any level on any class.

Legacy-Bound

GTN: These older armors were originally available in Galactic Command boxes in the 5.0 expansion, so you may be able to find the Bind-to-Equip versions left over from the previous expansion on the GTN from players who had extras leftover to sell, though they will likely be hard to come by, and expensive. The ones on the GTN seem to be the same as the ones on the Tech Fragment vendor, though I can't promise they don't change appearance, so make sure to preview them before you buy them on the GTN.