I've got the core rules. What to buy next?

[Darklone]

Actually, I was running a campaign with just the PHB for a while when 3.0 just came out. Funny how interesting games can be with human antagonists who are just as competent as you.

I'm not surprised that you liked it. Most of my Kalamar games feature more human/humanoid opponents than earthshaking dragon vs demon wars.

My biggest problem was the "expected treasure" for NPCs... I usually gave the NPCs less treasure and one more level (as supposed to) to even out their CR values.

 

[Bagpuss]

Dice?

 

[Greylock]

Not much to say here, as my collection is small. But I do wish I'd bought Unearthed Arcana when I re-emerged in DnD, instead of waiting of waiting half a year. Nice book to have if you are DMing. VERY nice book if you are a player.

Thing is, the neatest stuff in UA for the player is best taken at CL1.

 

[Thotas]

Well, there's a lot of stuff out there to choose from, and there are some fine diamonds out there as well as some real trash to sort through. As others have said here, which is which for you very much depends. And if you've just got the core books and are new to gaming, you almost certainly don't have the personal experience to know -- which is why you're asking for recommendations, I realize. Problem is, we have to ask questions about your tastes to answer you, and then you don't have enough background to know what our questions mean in proper perspective.

So I recommend you just play with the core for a while. That may entail getting some beginner adventures, so that's the closest thing I can come to recommending a purchase. Once you know what you like, these board will help you find a whole lot more of it.