I saw your old thread on the BST forum and came here to post this. My suggestion is to check a GP listing before you start each day... it saves you having to go to the guild on days when the required item is going to be more expensive than it's worth. Here are links to two different listings. I usually used the FXIAH one instead of the Titanictus one because it seemed to load faster, but they are both great tools: http://ffxiah.com/guild_pattern.php http://www.titanictus.com/tools/guild
Anway, the nice thing about these tools is that they are updated using player input at the beginning of each day IRL, and usually the lists have been completed within 2-3 hours of JP midnight. They show what items will be asked for depending on your guild rank, and how many points they are worth and how many would be needed to hit the cap. At the time of this posting, the FFXIAH list for today is already finished but the Titanictus one is not. I can't remember if the Titanictus one shows recipies, but I know that the FFXIAH list has links to the items' AH listings, which should show the recipe and have a link to the items' pages on FFXIclopedia, which makes it useful even for looking up fish... though I'd probably be going to Final Fishing next when researching fish.
As far as finding out what to horde and what not to, it's really best just to watch the lists day by day and see what shows up more or less often, how many points it's worth and how hard it is to make or obtain.
I hope this helps you out.
EDIT: When using the FFXIAH list, make sure you set the server to your own, that way you can see if the Jeuno AH on your server is currently carrying any of the item you need... just keep in mind that others use this tool as well, and they might gobble up anything that's easily available, so you've got to jump on things when you see them.
There are a few exceptions, like woodworking GP where you need to turn in 456 maple wands that you can just skip. Those are just ridiculous, anythign where you have to turn in over 10 items to reach max I take a harder look at.
Yeah, I hate that; today the Fishing Guild asked for 94 non-stackable Phanauet Newts for only 1k guild points. The Carpenter Landing's ferry goes through the area the newts can be caught once an hour for only a 5 minute window.
I hate fishing in Carpetner's Landing... 4 hours trying to catch the 6 Lungfish I needed one day (4000 GP for 6 fish SOUNDED nice) made me decide not to turn in GP fish every again on days that they wanted things from there. I did fish up that doomtoad NM while I was there, but I didn't get a drop. Too bad I couldn't have seen the orc NM instead. I always wanted his ring. I think I managed to actually catch 3 lungfish while I was there. Edited, Mar 19th 2009 1:57pm by LadyOfHolyDarkness