Mallselling multiple items, with individual prices or limits specified, seems to be fundamentally broken at the moment. The prices and limits aren't really attached to a particular item, they are in parallel arrays that are used sequentially. So, if a particular item can't be sold for some reason (nontradable item, zero quantity, on the memento list, etc.), its price & limit get used for the following item, and all remaining items are shifted over. <s>Worse yet, it appears that attempting to sell more than 11 items at once will reuse the price and limit values from the beginning, for each batch of 11 items.</s> EDIT: splitting into batches was being done OK, the problem is only within an individual batch.
I'm working on a fix now. Short term: do NOT use mallsell if both of the following conditions are true.
1. More than one item is sold with the same command (a single item should always work fine).
2. Any of the items have prices or limits specified (using the existing or default values should work).
EDIT: should be fixed in r7146.