Amazon offers the Ekobrew Cup Refillable K-Cup for Keurig Brewers for $7.28 $7.50. Clip the on-page coupon to cut it to $4.37. Plus, Prime members bag free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise shipping adds $6.53.) That's an all-time price low for a single refillable K-Cup and the lowest total price we could find for $2.

Update: The price has increased to $4.50.