hmmmm... now that you mention it, I noticed the same thing the other day... tried to buy some random commons with credits from an abandoned ALT account... and the first page of (very low priced) cards all gave errors when trying to add them to my cart.

...and then like you say: The next seller tries to undercut when dumping their spares, which has a ripple effect.

!PIZZA
!LUV
!ENGAGE