I'm not sure that explains the full extent of the issue.
For example, in public world 1776, there is a Beech 1900 for sale. Its price is $3,000,000. In the "aircraft for sale" list, it shows its value as $3,362,619. If I click the check box next to that plane, and click "buy aircraft at the bottom of the page," the new table lists the plane's value as $1,403,491,815. Surely, there's no way the plane (or any plane in AM) could possibly have a value that high.
If I click the "buy" link next to the plane (i.e. individual purchase rather than mass purchase), it shows the same plane as having a value of $2,260,594. I guess that would be book vs. appraised value. However, I guess I'm now a little confused about how a plane's "appraised value" is calculated, and what the significance is of that number vs. the "book value" number that you see on the previous screen. It just adds to the confusion over which numbers mean what.
Nonetheless, I'm sure the $1.4 billion is a bug no matter what.