IPB BBBs began to exchange hands within 6 months of actually receiving the game in 2006-2007.
People did not all decide to "flip" their game, UNLESS they bought multiples, which did occur in a select few cases.
You never saw the stupidity of "pre-order resale resales" equivalency either (2004-2006), because the concept did not exist, and people were generally smarter.
The overseas orders shipped first due enactment of the RoHS (Reduction of Hazardous Substances) law in July 2006.
Those went out in June 2006, and their were only around a dozen or so.
Late 2007 were the last of IPR reproduction games delivered to domestic consumers in the United States.
If I remember correctly the last game finally was delivered around November 2007, but I would have check my records.
The average price in early 2008 jumped from 1.5-2X the actual purchase pre-order price of $4500.
New potential owners were initially paying an average of between $6000-7500 in 2008.
Some were still lower, however, in the $5000-5500 range initially, as they moved from one collector friend to another.
Highest paid price was well over $24K in the 2000s, but that was for an original prototype.
NIB IPBs were offered at much higher costs for those that squirreled them, but I never tracked those sales, as ultimately were private deals with purchase agreements not disclosed.
The HUO prices have continued to grow until average flatline in 2012 for the present time of around $16K.
There were several periods where they spiked to nearly $19-20K.
Variances in the market and actual additional parts included in the sales vary the price at the modern time.
A fair number IPB remakes of the ultimate 191 total are still in the hands of the original purchased owners.
Of the original 14 true prototypes, 11 are confirmed in collector's hands, and one was lost in a fire, the two others are still MIA.
The direct pricing opportunities I have had to buy the machine personally over the years:
1996 - $8K (prototype, after Capcom closed their doors from a fellow collector who bought the game direct)
1998 - $12K (prototype)
2002 - $16K (prototype)
2004 - $4.5K (IPB intent)
2006 - $5.5K (IPB, the "weird" period due to price speculation, negative pinball "terrorists", and goofballs)
2007 - $6.5K (IPB)
2008 - $7.5K (IPB)
2010 - $9.5K (IPB)
2012 - $11.5K (IPB)
2012 - $22K (prototype)
2014 - $24K (prototype)
2015 - $16.5K (IPB)
2015 - $18K (special edition IPB reproduction)
2016 - $15.5K (IPB, potential fourth owner, passed between three other local friends)
There can be no "average" in this pricing with these listed costs above due to the dependency of regional market location, type, and condition just the offered values for reference in my case.
All pricing was based on USD, regardless of location.
You can only see market trends.
The continued average pricing is $16K for a "multiple HUO game" as many of the specific IPB reproductions have changed hands quite a few times now.