Myself, and I'm sure many others are tired of seeing the same cop skin running around Liberty City. The clothes store "doesnt sell police uniforms".
I recommend some command for any cop on duty, while at the duty locker position perhaps /uniform [id] which would let cops choose between 1 of the 4 cop skins.
The cop skin ID's are 201, 133, 173, 174.
Perhaps /uniform 1, /uniform 2, /uniform 3, /uniform 4 while at the PD doors (duty locker) could toggle through the cop skins while on duty free of charge.