Pool 1 (192,000 total)
Dragon Blade, 7,000 weight, so ~3.64% chance to show up.
Pool 2 (266,000 total)
Arrow Revolver 8, 10,000 weight, so ~3.75% chance to show up.
Exploration Journal 3, 10,000 weight, so ~3.75% chance to show up.
I don't feel like writing a script to dump+calculate it all automatically. Since the auction hasn't changed in so long, I can manually grab an item or two for you if you want to know the odds.
Other little tidbits... the auction time is configurable (just all of it's set to 1700), and the number of items that show up each time is too (just again, all of it's set to 2 with two pools per region). Duck Boots are in the auction list for the KR region (pool 2), but commented out. They'd be rarer than the book pages and start at a million gold if they were active there.
EDIT: Eh, might write a script later and then post the results in a thread, I just get annoyed cross-referencing item IDs to double-check stuff.