PRICE_UPDATE
id (int 5,auto-increment,primary,unique)
part_number (varchar 10,non-null)
price (float(10,2),non-null)

DELETE t1
    FROM YourTable t1,YourTable t2
    WHERE t1.part_number = t2.part_number
        AND (t1.price,t1.id) < (t2.price,t2.id)