Prestige Milano via Amazon offers the Vilros Raspberry Pi Model B+ bundled with a Raspberry Pi Enclousure Case and Realtek Wireless WiFi Adapter for $36.99 with free shipping. That's $6 below our November mention of a similar board and the lowest total price we could find by $23. Features include a 700MHz Broadcom BCM2835 processor, 512MB RAM, WiFi adapter, Micro SD card slot, Ethernet port, micro USB 2.0, USB, and HDMI output.
Don't need the case and adapter? Micro Center offers the Allied Electronics Raspberry Pi Model B+ Board for $24.99 via in-store pickup.