Please excuse my delay in getting back to you newmagrathea, it's been a busy few weeks which is rare for me lol!
I did have a huge (and on-going) search for you but no luck yet. I think I just got lucky with the grip/switch part. The greeblie is more than likely a 'use once only' type of part, as you can imagine, so the relatively few made are either still in aircraft or in spares stores sat on a pallet.... in a dusty hanger.... under crates marked 'danger! do not open! melty face, melty face!' (Hopefully there's not a member here called 'Meltyface', cos that would be a tad awkward, lol).
Great work on the 3D model starving4rtist, it looks like you've got all the details down. Just one thing, the pin in the trigger in the film prop is poked through the other way around - so the flat head is on the opposite side to the real part in my pics. But if you are printing the whole grip with a seperate trigger and pin then forget about this last sentance and here's your 15 seconds back [ 1 x 15 seconds ]
Great stuff!
You could make the grip handle / tube hollow, that would resolve the column fixing problem.