Northern Tool discounts over 600 air compressors, air tools, and associated parts and accessories, with prices starting at $3.49. Plus, take an extra $10 off orders of $50 or more via coupon code "254879" or an extra $20 off orders of $100 or more via coupon code "254876". Where available, opt for in-store pickup to avoid shipping costs, which start at $5.99. (Free shipping is available for select items.) Coupons expire October 17. A couple of best bets: Note: Free shipping requires you unload items from the truck yourself. If you do not have the means to safely unload these items, lift gate service incurs an additional charge.