Cosplaysky do a good black imperial officer uniform (get the version 2 one as has been improved by feedback from members)
Don't get the hat and belt buckle though. You can talk to sideshowmel for good quality hats and muppet for belt, buckle and disc to put on the hat.
That would leave you boots, rank badge and code cylinders to go.
Boots can be got from places like horseland just hope you don't have large calves.
Rank badge Tiggie from the imperial officer site imperialofficer.com or fx.guy
Code cylinders there are people who sell resin copies or you can convert a chalk holder. Tutorials on the officer site
Otherwise ask as many questions as you can as there will be someone who's been there all ready and can point you on the way
Oh and welcome