When you own a ship, it becomes possible to get negative prices by doing long enough, mostly by ocean, reckless fast travel by ship.
I think it comes from
Code: Select all
travelTimeInHours - pixelsTraveledOnOcean
becoming negative as time travel grows by 51/2 minutes per ocean pixel only. In theory it may happen with cautious traveling too since 51 minutes is also under 1 hour.
That's a known bug in Daggerfall classic also.