I have a silver shrimp fork in my store, priced at 999,999,999. When I click the "auto reprice" button in the Store Manager GUI, it fails to reprice that item, regardless of whether I click "Yes" or "No". That's the only item I have in my store that's affected in this way; it'll successfully reprice everything else. Also, I'm able to enter a new price manually.
KoL's mall pricing page says it has an autoprice value of 235 (and a minimum sale price of 470), but the item description doesn't mention this and instead says it can't be discarded.