Seeds, plump helmets, booze all get requested, along with whatever random crap I am missing for whatever I happen to be working on. I then proceed to buy out all wood, booze, seeds, meat, cheese, important gems/metals, and the like. I also grab a few bins of leather, cloth, and a few chunks of glass for moods. I always get as much food, seeds, and booze as possible, because to quote a famous story of ye olde times, overconfidence equals starvation. It's weird though, I've yet to really hit situations in my forts where food is an issue, yet I always seem to stick to always amassing these basic items. I usually end up having a dry spell of 3-7 days of not playing due to classes, so I'll start a new fort before my previous fort has gotten into its 2nd or 3rd year. As a result, my experience with things like the military, mega projects of doom, etc is lacking, so I always end up raiding caravans for the bare basics.
That and it's always satisfying when you turn a fraction of the food bought into prepared meals, then trade a stack or two of them for an entire caravan of food and whatever crap they have.
If there's cheap misc. items, like buckets, splints, empty barrels, etc that are reasonbly priced (IE not studded with gold from outer space or whatever), then I'll buy those too just to save me the effort of making that one extra unit of it. What else am I going to do with 5000 metric fucktons of granite/schist/dolomite/limestone/whatever scepters? =|