Amazon offers the Sharpie Metallic Fine Point Permanent Marker 12-Pack for $2.85. Check out with Subscribe & Save to bag free shipping. That's about $17 under the price you'd pay for this quantity at your local store.

Be sure to cancel your subscription after receiving your item to avoid being billed for subsequent shipments.

Update: Subscribe & Save is no longer available; however, it's still available for Prime members for the same price. It's expected to ship in one to two months.