Another update for posterity - this was after a light drop caused the viewfinder prism to seperate in my M2, causing a complete blackout.
I ended up having my M2 viewfinder repaired by Ernest Cesar at Camera Electronic in Perth, WA. The M2 came back looking fantastic - there is no visible sign of separation either when looking at the M2 generally or looking through the VF.
The repair wasn't cheap (what is in Leica land?) but given that it came in at about 1/4 the replacement price of a good M2, it seemed like a good option for a body that I know is otherwise in great working condition. It only took a couple of hours labour too, so a pretty quick turnaround.
A important thing to keep in mind - Ernest reiterated that these repairs are time critical, as the separated prism will begin to oxidise if left for too long.
Good to know for us Australian's that there's a solid local option without having to send our gear to the States!