Mass market kits:
In hobby shops
Polar lights:
350th Refit E
1:1000 TOS E
AMT/Ertl
1:2500 set TOS E / E-A / E-D (reissued)
1:2500 set E-B / E-C / E-E (reissued)
On ebay
AMT/Ertl
650th cutaway TOS E
1:1400 E-D
If you look around the net you can find a ton of different resin and vacuum form Garage kits. I'm not sure if thats what you where looking for but hope it helps.