Building a guild and setting its defenses. (need resources)

I am implementing a "Guild Credits" system for players who write journals of what their character experienced in the previous session, as well as completing quests.
I'm using the hyper inflated values of 3.5, because 1) it's a company - it's supposed to be about big bucks, and what better way to represent guild progression than to use much more gold than you should ever get for your personal character, and 2) there are more resources for this sort of stuff as a result of longer development time.

So, I've got that Stronghold Builder's Guide (I think is the name), and that's a great place to start off with. I know there's a Dragon Lair book, which has magic trap thingies for its lair. I have no idea what the name of it is though. I am also using a third party golem/animated item book, for which I wrote my own program for, and they will be the more mobile of the guild defenses (though still restricted to no more than 10 feet from the guild hall itself).

Most traps should probably be avoided unless it has a trigger that only a guild member can use, otherwise clients or even the other members, could be harmed...but considering there are kobalds as part of the guild, letting them use it...lol. Well, actually, despite their intelligence, traps are supposed to be their specialty......not the point!

Other than that, their recruits and hirelings serve as the guild's defense...infrastructure...everything that the players don't want to deal with personally, or literally can't deal with (such as if they are on a mission) - yes the party said they liked the idea, it's not just throwing a big middle finger to them out of nowhere to have their guild come under attack.

So, my question: what other books are a good resource for this sort of thing? What ideas could you offer to make this aspect a bit more enjoyable? Also, what is a reasonable gold per session, when this is the only thing (along with other "not-directly-impacting the characters' stats" expenses, like bribes or what have you) that the characters will spend these "Guild Credits" on?

The DMGII has rules for Guilds on page 223 though they are a bit basic. It outlines what guild types there are and if you join one you get bonuses to skills. If you take either the Favored in Guild or Guildmaster feats you get some bigger benefits like buying items cheaper, lower item creation costs, benefits in combat and so for.

The PHBII has rules on Affiliations on page 163. These are all guild-like but cover a lot more ground. These range from local church organizations to capital city thieves guilds to nation wide trade companies - they vary greatly in type and scale. The benefits for joining these is better defined and according to your standing in the affiliation you can get skill bonuses, resistances, government support, divine spells cast for you, caster level bonuses and more.

If you implement one or both of these, maybe you'll give your players more incentive to participate and expand the guilds.

Hmm. Did I not say it explicitly? Well, I am now. The group are all guild masters of their guild.