What the PCs don't know is that (at least in my world) Yoda's line about "Always two there are..." is wrong. Darth Bane survived the Sith Wars, as did one Sith apprentice, who founds his own Sith order. This off-world business man is a master of this New Sith order. Having to avoid other Sith, the Old Republic, and the Empire has taught these Sith even greater stealth.
They are like Ninja...trained in stealth, poisons, weapons, disguise, etc...plus the Dark Side. (I'd give them a feat that lets them avoid being sensed by other Force users, even while they use their powers.) He has orchestrated the theft of his own holocron, having one of his Disciples (apprentices) "steal" it. He tells the heroes that his planetside contacts have tracked the crystal to a certain area of the city. They recommended hiring these particular bounty hunters and their friends.
The place they are told the thief is hiding is a large dark warehouse filled with booby traps. If the heroes make it to the center of the warehouse, where the crystal can be seen by the light of a single fusion lantern. When the heroes approach the holocron, 12 masked figures step out of the shadows. As each steps forward, he ignites a red lightsaber.
I'd set their levels so that it would be a tough fight, but the heroes will live (barely). When the last ninja/sith falls, a larger masked figure (wearing a cloak and more elaborate clothing, unlike the rather plain black garb of the 12 disciples) drops from the rafters, carrying a double bladed lightsaber. He (actually the businessman/sith master) grabs the holocron and makes his escape.
