I know this an old thread, but I just went through this and thought I'd throw in what I found out.
Tesla will not sell trim separately, so that is just simply not an option.
My motivation was to change from vertically-oriented obeche wood trim to the new horizontal style. Maybe I'm OCD, but I think the look is much better.
I actually removed all my dash trim and traded with another forum user. It's pretty straight-forward and only took me a couple hours, and I went slow to make sure I didn't damage anything. Every screw is a Torx 20 and there's maybe 15 of them total for all three pieces on the dash. A lot of the lower pieces under the dash just pull out. Once removed, you could swap or wrap your current set.
The best instructions I found didn't include many pictures for the trim removal portion, but I ended up not needing any:
http://www.teslarati.com/how-to-add-a-carbon-fiber-interior-trim-wrap-tesla-model-s/