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