It would be more expensive initially in time, and I'm sure you'd charge more per shirt, but it would all average out over time.
I'm not trying to cheapen this awesoem artform at all, but for those that don't understand it, you can liken it to modern rubber stamps. You get the stamp made, you put ink on the stamp, and you press it on your substrate.
The difference is the distinctive look of a woodcut (which, yes, CAN be simulated), and the knowledge of the way these shirts would be produced.
M.C. Escher used to use this method a lot for his work.
The Official M.C. Escher Website