Sears offers the Monster 1,650mAh PowerCard in Silver, Red, Blue, or Black for $19.99. Opt for in-store pickup to avoid the $5.99 shipping charge. That's $10 under last week's mention and the best price we've seen. (It's also the lowest price we could find in any color now by $16.) It's compatible with most USB-driven devices.
Of note, Shop Your Way Rewards members will earn a Sears credit with this purchase and may be eligible for additional credits and discounts. Plus, Shop Your Way Max members are eligible for free shipping.