I think the custom one is a series I with some additional knobs. Could be totally wrong of course. The top looks great on that guitar.
The Orion looks nice and I guess compared to a new guitar its a decent deal, but unless that redwood top is some kind of crazy expensive top then I would have to say that the guy is asking a lot. Ive looked at a few used Orions and they tend to be in the low 1000 dollar range. I guess his price isnt too bad, but he did start out at around 2500 and that was very high. You could get a brand new Orion in that range.
Both are nice, its nice to see used Alembic guitars, not many of them are out there that I see at least.