See, I know nothing about figures! I just assumed standard size was about three inches, because that's the size of the ones I had when I was a kid. And I think they were from that series! I am actually looking for something more like an inch and a half -- like little army man size. I thought of getting model paint and painting army men to look like Trek characters.
Try these: Micro Machines Innerspace Playsets
. They're tiny playsets with itty-bitty figures accompanying them. They don't have articulation, but if you're okay with that, they might work. I think they're, like, a half inch tall or something. Pretty tiny.
Then again, for the price you might be better with your painting idea. There's only two characters per playset, so you'd have to buy a bunch to get the whole crew.