I'm not too interested in dressing like a miner, either. But that costume is so flexible, you can do all kinds of outfits with it that don't look like a miner at all. The pieces have large palettes and can be used pretty freely with other costume parts. And it can be worn by boffs, too. Overall its a great costume and much more worth buying than the Embassy robes.
My only problem with it is, Fed-Rom can't use the wrist computers with it.
But then those can't be used with most other things either, so nothing new there.
You have to be part of a Fleet with the Dilithium Mine Fleet Holding...
You don't have to be part of the fleet. You just need an invite to a mine holding that has it unlocked. And it doesn't use a provision, so you don't even need to be in any fleet to buy it... just costs fleet credits and dil (8k/16k).