Tematika Pricecheck:
Not having any books with Argentinian ISBNs, I tested by changing a few ISBNs to their complementary Argentine versions. In my tests, everything worked.
@Dunhill, please let me know if you have any issues.
You need to manually create the two custom columns (one for price and one for date which must be in date format) and then put the column labels into their respective textboxes in the configuration of the plugin.
Columns example:
