Northern Tool offers the Roughneck Air-Operated Double Diaphragm Oil Pump for $379.99. Plus, coupon code "260227" bags a $50 Northern Tool Gift Card for free. Opt for in-store pickup to dodge the $17.99 shipping charge. Assuming you use the gift card, that's a savings of $70 and the lowest price we could find. It features solid cast aluminum construction and nitrile diaphragms. Deal ends June 25.