Which item provided to a project whose main subject area is Literacy & Language has the highest unit price?
main subject area refers to primary_focus_area = 'Literacy & Language'; highest unit price refers to Max(item_unit_price);
SELECT T1.item_name FROM resources AS T1 INNER JOIN projects AS T2 ON T1.projectid = T2.projectid WHERE T2.primary_focus_area = 'Literacy & Language' ORDER BY T1.item_unit_price DESC LIMIT 1