With availability very limited by ZIP code, and for in-store pickup only, Best Buy offers a selection of Dynex Cables and Charges, with prices starting at $1.99. A couple of best bets:
Dynex MFi-Certified 3-Foot Lightning-to-USB Cable for $1.99 (pictured, $6 off)
Dynex 2,000mAh Portable Battery Charger for $1.99 ($6 off)
There's a less expensive way, and then there's the way that works for you. The two may not be the same.