The only thing I can think of that influences this would be a mod, and I've installed HotFusion's Economy Adjuster with MPP v 1.6.4 that might make changes to all the merchants in the game. The only other mod I can think of that might do this is Service Requirements v 1.4.3 (original mod by vanhikes, updated by makeshiftwings) which modifies certain service requirements. But this doesn't affect every merchant in the game, so I think it's an unlikely culprit. I also noticed that Object Permanence v2 uses TakeMeToYourLizard's Fashionable Merchants as a template for part of its scripting. This IS likely to affect merchants, so it might also be to blame, but I don't know.
Does anyone have any ideas? As I'm sure this is a mod issue, I've posted it in the mod forum. If it belongs elsewhere, could a mod shift it to the software/hardware issues forum?
Thanks in advance!