It's an interesting proposition, but my intention has always been to find where I can be of greatest leverage. SpaceX is at a place in time / life / hiring that I think I wouldn't really be able to contribute to its mission (and mine) as much as I might by doing something else first. That plus I doubt I'd be of terrible appeal. The following are also true:
a) SpaceX appears more specifically to be looking for rocket engineers, etc, a background I do not have. (Good business / analytics / etc, but, a rocket engineer I am not). This problem likely applies to Planetary Resources as well. However...
b) Planetary Resources is more directly aligned with the mission I find most important - SpaceX is doing great things, and Elon Musk is super cool for insisting on his goal of making humans a multi-planetary species, but that's still a ways out. I don't know that I'd have as much ability to contribute. It's for this reason I've been trying to gain skills that would be of greater value down the line (business ones, in particular) in order to do what's necessary to help run and grow a commercial space venture.
c) I actually asked Elon Musk something on the subject - 'What advice do you have for people interested in getting involved early in these kinds of capital-intensive but world-changing businesses' and his answer was that, of course, it's helpful to have a few $100MMs from something like an internet company first :)
Have you applied for a job at SpaceX, yet? That's one way to get involved with modern space faring.