I'm thinking about getting into Pathfinder. Unfortunately I can't find a gaming group in my area so I'm up a creek. I'll probably be relocating in a few months anyway so I guess it's not such a big issue to be game-less at the moment.
Since I'm not going to be playing for awhile I'm almost more interested in purchasing the Campaign Setting book instead of the Core Rulebook. I have some familiarity with D&D 3.5 so I can see how characters will generally look even without knowing Pathfinder's changes. It's the world I'm interested in.
Would anyone advise against this? Is there something vital I wouldn't know from not having the Core Rulebook that would diminish my understanding of Golarion?
I'd say no. Go with what you're going to enjoy most for now, and pick up other stuff as your situation changes. If you're familiar with 3.5, you'll pick up Pf really quickly. Plus, download all the free stuff, such as the conversion pdf, for extra reading/preparation for eventual play.
Not at all. The Campaign book came out first and was initially designed for use with 3.5. The core book has no setting detail (other than presenting the Golarion gods as the new default gods) and isn't necessary for using the campaign setting book.
Buy the Gazetteer in print (in comes with a superior map, anyway), and the Core Rulebook in PDF. Under $30 for both, and you get to scratch both itches. :)
What Abe said.