eBay.com has this BlueAnt S4 Bluetooth Hands-Free Car Speakerphone Kit w/ Dual-Phone Connectivity for $24.99. This kit ships for Free, and features include:

• Text to Speech technology reads out the name of incoming callers
• Stores up to 2,000 phonebook entries per paired device
• Embedded audio help talks you through setup and operation
• Multipoint: connect to 2 phones at a time and answer the one that rings
• A2DP streaming for playback of music, podcasts and directions from a GPS application on your phone
• Full duplex, high volume speaker for rich booming audio
• Outstanding wind, road, and background noise reduction for clear calls no matter how noisy it is
• Sleek design with touch sensitive volume controls
• Zero installation costs (fixes to the car sun visor)
• Hardware on/off switch
• Up to 20 hours talk time; 700 hours standby
• Bluetooth 2.1
• 2.4 GHz Frequency
• Bluetooth range, up to 33 feet
• Micro USB Connector
• Charging Time: 3 - 4 hours