What are the best books to get

[Bowen Fitzcairn]

Ok, so I am a long time gamer, but new to Pathfinder, I picked up the core rules and the bestiary, so I have the bare essentials of what I need to either play or run a game. Having been a player of 3.5 D&D and having amassed a fair collection of splat books for that, I was wondering where to go next books/supplements wise. I have thumbed through a number of the books out there for the Pathfinder system and they all seem to be pretty packed with useful options, but I don't have the disposable income I did as a younger player so choosing that next purchase takes on a bit more weight. I just thought I would seek some advice from the boards and see what some of you might recommend. I know there is probably already a thread or threads out there about this very topic, but I also wanted a good entry into the forum, so here I go. Any suggestions will be appreciated, thanks in advance.

[Rynjin]

I'd say save your money for APs and just use the D20PFSRD for the splatbooks, since everything is on there.

[Lincoln Hills]

You will find the Advanced Players' Guide probably the most broadly useful after the CRB and Bestiary 1: it introduces some optional new base classes, provides the concept of 'traits,' 'archetypes,' and 'Hero Points' as well as some new Combat Maneuvers and optional variant racial abilities, and provides an array of new spells and magical items. The archetypes are particularly useful for a GM, who can get a lot of mileage out of them when designing NPCs with a particular role in mind.

[Seriphim84]

If you run alot of APs then I agree with Rynjin mostly. The only exception being the first book on the list below.

If not, then go in the following order:
Inner Sea World Guide - A great addition with tons of information about the world and a good amount of crunch as well.
Advanced Players Guide
Ultimate Magic
Ultimate Combat
Advance Race Guide
Ultimate Equipment

There is also the Game Masters Guide but I use it so infrequently I don't recommend it until you have everything else.

Then there are the hundreds of little specialty books out there. If you buy these I recommend getting them in PDF to save some money, they are great but not used enough to need print additions.