BlueRigger via Amazon offers the Kinivo Bluetooth Hands-Free Car Kit, model no. BTC450, for $35 with free shipping. That's tied with last week's mention and the lowest total price we could find by $7. It's compatible with Bluetooth cell phones and Apple iPhones and features a microphone, music controls, and adhesive pad for mounting.
Note that this car kit requires a 3.5mm input jack in the car stereo.