B&H Photo Video offers the Eye-Fi Pro X2 16GB 802.11n Wireless SDHC Secure Digital High-Capacity Card, model no. EYE-FI-16PC, for $77.95 with free shipping ($4.88/GB). Sales tax is added where applicable. That's the lowest total price we could find by $12, outside of the mentions below. This card stores pictures like a standard SD memory card, but it also connects via WiFi directly to your PC or Mac (no router is required).

Two close prices: Adorama has it for $79.95 shipped and Overstock has it for $79.99 shipped.