+1 for tribolube - I use tribolube 71 on the rEvo and it's the only 02 compatible grease recommended by the unit manufacturer.
He even states that we should use it on non-02 components for the sake of uniformity and not getting silicon grease on the 02 side
I know some of the RB dives in the club buy ChristoLube from LDS. It is ordered from Scubapro as a service consumable and comes as a big tube. Can't remember what they said they paid for it, but it was quite a bit cheaper than getting it elsewhere.