From what I've read the Cell is composed of a number of chips, the main processor is similar to a PowerPC and it routes requests to the Cell chips that surround it (8 if I remember correctly). Sony is producing the Cell chips, IBM is producing the PowerPC-like component.
Also, $200-300 for just the drive sounds about right, considering that a set-top box with the processing and decoding hardware is going to cost $1000+ retail.