(i.e., does business with Dharma, eventually hears about this weird island, wants to find island in order to exploit it for gain).
I forget a lot of stuff about the show, though, so it's possible it was more strongly implied that he was Dharma and I forgot.
I think it was strongly implied that Widmore had been on the Island at least once, that he was trying to find it again. If he were part of the Dharma Initiative, that would make sense. I never considered that he started out there to begin with!