In my 944, I have this unit installed. It is the only non-original piece in the interior of the car.
Amazon.com: JVC KDX250BT Digital Media Receiver Bluetooth Front USB-AUX: Car Electronics
I found that I couldn't live without a bluetooth device in my car as I got so used to my DD being equipped with it. The sound is good, but the phone works fantastically. It has a separate microphone for the hands-free that I mounted just behind the steering wheel, below the gauges. I have a small windscreen on the mic. Even with the windows down and the roof off, I have never had anyone complain that they can't hear me or it is too noisy.
Based on your wish to keep price down, this may be a good option.