Jeff, I doubt you will be able to keep the polyp color on the rainbow monti under VHOs.....it will most likely look like rusty colored polyps on a blue/purple base.
Maybe if you could find a piece of the original tyree rainbow monti, you'd have a chance because it has been in captivity for a good while, but in my experience, your tank has to have BRIGHT lights, and very good parameters to keep the nice polyp colors.
the blastos, you can probably find at many of the local stores.....the rainbow might be a bit harder to find, though I've seen a couple local reefers with frags! I have a rainbow monti colony, but if a fish spits out a pellet in my tank at work, the rainbow turns brown again in my tank at home. I know the colony in the display tank at WWC is the same way, though a bit better than mine.