I bought the same one for 5k but it was the day AFTER I bought the same schem for 400k from a guildie D:

Well, for magenta crystals they have +16 crystals that drop off of the Alderaan, Nar Shadaa, and Tatooine World Bosses.

The crit schems are also from Black Hole mobs, one of my guild members just looted it the other day.

Thank you for the clarification, heading to Alderaan now to check this out. I don't remember seeing any posts about a spawn point at South House Thul Steps, but I'll check that area anyway.

I'm not sure if the respawn timer is 2 hours because I came back 2 hours later and waited around a bit and neither node has respawned. It's possible that they respawned at undiscovered locations i guess...

I found crystal formations at both of these locations on Sanctum of the Exalted (I don't think many people are looking for them here, I've only seen one on the GTN). After I picked them up, I soloed Ulgo Siegebreaker to see if I could get a schematic, but he didn't drop one, so I can't confirm that he drops these. I'm now testing the 2 hour respawn on the crystals and I will continue downing the Siegebreaker to see if he drops a schematic.

Consider yourself lucky, I have literally made 25 and not a single saber has been critted

For me, the chest had bugged when I first unlocked it, and after being unable to beat the fight by myself I left to pick up a guildie to help me. When I returned, the box was fixed, so I think you just need to leave the area and return to make it work.