In thinking more about this: If a script is written that checks for all of the items on someone's "wish list" then too many people will have it running which hammers the game's vendor search system. I don't think a UO dev would have to work too hard to find people who look for "insert uber item here" every 5 minutes around the clock, ya know? And they would look, that system is resource intensive.
Perhaps a better idea: a manual list where you would have to manually click on previously entered items(no typing, yay), or as one of my favorite auction house addons did in WoW a history list of things you've searched for that allow one click re-search.(no typing, yay).
Or another way to go: A script that creates a targeting cursor so that when you click on an item in your pack it launches vendor search for that item. This would run into the problem that some words are too vague, even if they are part of an item name. UO throws an error when you use them so some parsing to get rid of them would be needed.
*NOTE*: That last method could employ a "last checked" date with the value it found then if you are not in your house or at a bank, such as when you are standing at someone's vendor or deep in a dungeon.
Which do you think would work best?