Yes, they were an "exclusive" item for Star Trek Season 3 bluray owners I believe. Although pretty much everyone has them, because the unlock key made it's way around the internet. These days you can also buy them in the C-Store.
Actually, they were hardly 'exclisive' as the code in the Blu-Ray box sets was not unique (ie EVERY box had that same code, so once it got onto the internet, anyone who wanted it could find it - Cryptic recently made it a 'free unlock' though).
But yes, you can currently make uniforms from any Star Trek era (except the 22nd century Enterprise
) and even the Mirror Universe now as all the pre-order costume perks were added to the C-Store. Most ' other era' uniform sets are about $3.00 a pop (240 Cryptic Points per) and there's TNG, TOS, and DS9 (the DS9 ones include the TNG 'First Contact' movie uniforms as the show started using them in the 5th season).