Could you shed alittle more light on the companies that do the retrofits? I'm in Seattle too - and yes, I wish my seats were heated 'cause they get cold, cold, cold after siting in the parking lot at night.
If you know, is the basic wiring already in place? It would be nice if you just had to cut some holes in the console, drop in the factory switches and then add the pads to the seats. If it takes new wiring, I'd imagine that cost a weee bit more to the price tag.
Also, is there any impact on the alternator? The stock alternator is my '95 E420 is 105 AMPs. I can upgrade to the 143 AMP alternator from S420, but that's around $300 for the part. I'm just mentally totaling this up and seeing a possible project cost of a $1000 after everybody gets their labor.