A4C via eBay offers the Motorola TX500 Bluetooth 2.1 In-Car Speakerphone for $14.95 with free shipping. That's tied with our April mention as the best price we've seen. (It's also a current price low by $5.) It features up to 45 hours of talk time, up to six months of standby time, ambient noise reduction, and connection to two phones simultaneously. Deal ends today.
Note that although this item is brand new, it ships in bulk-packaging.