Auction House Mechanics

Introduction

A while ago I submitted this information as a guide to GameFAQs, but they rejected it for being too specific in its content, so I decided to post it here instead.  I was able to obtain the details of how the auction house works through a script provided by marcelloc2.

NOTE: In the formulas given, the result of anything in square brackets [] is rounded down to a whole number.

The Items

Availability

This section will outline in brief what items can be purchased from the auction house and when.  You first gain access to the auction house when you visit Treno in early disc 2 with Dagger.  You will return to Treno at the beginning of disc 3, at which time there will be new items available for purchase.  Once you gain a form of transportation a short while later, you are then free to return anytime you like, and more items are available.  Many items have restrictions placed on their availability which are explained below.

From Disc 2 on:

• Mini-Cid* (Key Item)
• Griffin's Heart* (Key Item)
• Magician Robe
• Doga's Artifact* (Key Item)
• Fairy Earrings
• Une's Mirror* (Key Item)
• Madain's Ring
• Reflect Ring**
• Pearl Rouge

From Disc 3 on:

• Anklet*
• Rat Tail* (Key Item)
• Feather Boots*
• Dark Matter**

After Obtaining the Blue Narciss:

• Elixir***
• Promist Ring*
• Thief Gloves**

Disc 4 Only:

• Magical Fingertip**** (Key Item)
• Ribbon**

* You must not have this item in your inventory in order to buy it at the auction.  If the item can be equipped, you can simply equip all copies of it that you have, and the item will appear again.

** Can only be bought from the auction once.  Once you buy it, it will never appear again.

*** You must have fewer than five Elixirs in your inventory in order to buy an Elixir.

**** The Magical Fingertip is part of the Excalibur sidequest.  To get this item to appear in the auction, you must have previously bought Griffin's Heart, Doga's Artifact, Une's Mirror, and Rat Tail and sold them to the interested buyers around Treno.  You can only buy the Magical Fingertip once.

Item Selection

There are four items up for sale in every auction, and each item will only appear in its designated position (i.e. 1st, 2nd, 3rd, or 4th).  There is a predetermined order in which the game will check each item to determine which one will go in each position.  As long as all requirements are met as outlined above, there is a certain chance that the game will choose the item is currently considering.  It moves from left to right in the following table, and the chance that the item will be selected is given at the top of the column in which that item appears.  The 4th position is an exception.  For 4th position, the chance is always 100%.  Thus, the Dark Matter will always be chosen until you buy it.  This will be followed by the Thief Gloves, and so on.

	75%	50%	100%	75%	75%	100%
1st Position	Mini-Cid	Anklet	-	Rat Tail	Griffin's Heart	Magician Robe
2nd Position	-	-	Elixir	Feather Boots	Doga's Artifact	Fairy Earrings
3rd Position	-	-	Magical Fingertip	Promist Ring	Une's Mirror	Madain's Ring

4th Position

Dark Matter

Thief Gloves

Ribbon

Reflect Ring

Pearl Rouge

For example, if the requirements are met for all the items in the first position, the game will first check for the Mini-Cid.  There is a 75% chance that it will select the Mini-Cid; if it does not, then it will next check the Anklet at a 50% chance, and so on down the line.  If it gets all the way to the last item on the right, then it will definitely choose that item.

To get the 75% chance, the game will pull a random number and check to see if it is divisible by 4.  If it is divisible, then the game moves on to the next item.  If it is not divisible, then that item is chosen.  A new random number is pulled for each item.  For the Anklet, which only has a 50% chance, an odd random number will cause the Anklet to be chosen, and an even number will make it move on.

Prices

Initial Setup

Each item has a base price which controls its price range.  Here I have listed the base price for each item.

Mini-Cid - 2531
Anklet - 12656
Rat Tail - 16875
Griffin's Heart - 5062
Magician Robe - 5906
Elixir - 26250
Feather Boots - 13125
Doga's Artifact - 7000
Fairy Earrings - 7000
Magical Fingertip - 45312
Promist Ring - 21750
Une's Mirror - 10875
Madain's Ring - 6343
Dark Matter - 13593
Thief Gloves - 22656
Ribbon - 63437
Reflect Ring - 10875
Pearl Rouge - 12687

The following formula is used to calculate the initial value the auctioneer starts the bidding at.

Initial Value = [Base Price / 512] * 100 + 100

Each of the five nobles at the auction will then set his/her maximum bid to a random number between 50% and 150% of the base price.  If the auction is at the 4th item, then the nobleman in the front row will have his maximum bid doubled.  Then, any noble who has previously bought an item in this auction will reduce his/her maximum bid by half of what the maximum bid for that item was.  For example, if a noble bought the Rat Tail in this auction, and that noble's maximum bid for the Rat Tail was 21,532, then that noble's maximum bids for the rest of the auction will be reduced by 10,766.  It doesn't matter how much the noble actually paid for the item -- just how much the maximum bid was.  There is a hard limit of 95,000 for the nobles' maximum bid.  This really only applies to the Ribbon because nothing else can go that high.

The Bidding

Now we'll get into the nuts and bolts of how the nobles bid.  Each time the game selects a noble it executes the following script.

1. Generate a random number between 192 and 255 (hereafter referred to as RND).
2. Set the bid amount to be [(CurrentHighestBid * RND + MaximumBid * (256 - RND)) / 25600] * 100.
3. If the result of this is higher than the current bid, then the noble will bid this amount and the bidding process will start again with the next noble.
4. If not, then there is a check to see if the current bid is less than 129/128 of the noble's bid.  If so, then it generates another random number from 0-255 and sees if this number is less than CurrentHighestBid / 128.  If this is also true, then the noble will say "Hum...".  Then, as long as the noble's maximum offer is not more than double the base price and is less than 90,000, then the noble will increase his/her maximum bid by 1/256 of the base price.
5. Whether or not anything happened in step 4, if the noble did not place a bid, then a timer will increment and it moves to the next noble.  This timer resets anytime a noble places a bid.

The game then picks a noble at random and goes through the process again. When the timer reaches 5, the auctioneer will say "I just heard " whatever the current bid is.  When the timer reaches 20, the auctioneer will say "Any more?"  The item is sold when the timer reaches 36.  It's not clear whether or not this was intentional, but bids made by the player do not reset the timer, so if you make a bid after the auctioneer asks for any more, there's a chance you'll win the auction before the noble you're bidding against has a chance to even consider bidding again.

YouTube user TheLilGecko discovered a bug where, if you place a bid just as the noblewoman in purple starts to raise her arm, then she will bid the amount you entered instead of you. The window for doing this is very small, but I can confirm that it is possible to do on a console. I just haven't been able to do it on purpose.