The Kirk costume in the Piece of the Past Star Trek auction is a mix of a Shatner undershirt and stunt vest and pants. Interestingly both the vest and pants have slits in them for what was probably wires for a stunt rig,
This is an important costume, even though it is mostly stunt. And I think it is worth $ 4-5,000 or so. I hope these close ups help some.