Yes, I think searchuo just uses bots to go around looking into packs. It covers all of Luna as well as some vendors outside of Luna. I wouldn't be surprised if searchuo is omiting known rares however since they want to get/sell/collect those themselves. If you search atlantic's vendor search for "catskills" for example you see a bunch of catskills EM event items but searchuo does not show you these items.
Anyway, right now I've got a wishlist of items in notepad++ and am manually using UO's "vendor search" to check them each one by one. Items like a "secret chest" are rarely on a vendor so if one shows up I want to know as fast as possible. That chest is from an Asian shard event and so isn't common on Atlantic(it allows 500 items to be stored in it, not 125).
So there isn't a search script that works with the default UO "vendor search" feature? I really don't want to wander around from vendor to vendor with a script since the vendor search feature already has that info.
I don't have a screenshot, just an idea, a script to run through a list of items I am looking for to tell me if yes/no the item was found. Since I'm going to use it to search for rares a simple found yes/no is enough since there won't ever be a lot of them.