I've also always wanted to do this, but finding figures is tough.
There aren't a lot of generic suited figures out there for the base troops, and of couse, anyone unique is..um...unique.
Still I wanted some so I modified and repainted some figures just to have some, and I think it's a good start.
This was a few years back, and when I get more serious about it I'll re-do them better. But they work as a proof, and for the ocassional bad guys.

They are all modified/painted Clix figures.