The Inquirer writes motherboards for AMD's new Socket M2 and AM2 will be $5 to $10 more expensive than the current motherboards.
Socket AM2/M2 boards will use DDR 2 DIMM sockets only, so you can say goodbye to DDR 1 memory. DDR2 sockets have been around for more than two years now, thanks mainly to Intel of course and their cost is already equal to DDR1 sockets. No change here.
The maximum thermal dissipation will remain very close to existing socket 939 CPUs but AMD will introduce a new improved mounting for the new heatsinks. The improved mounting uses four holes instead of two. We don't know whether you'll be able to use the old Athlon 64 coolers for these new boards or not. Something tells me that you should be able to do it.
In the beginning these motherboards wil be a bit more expensive to make but after some time the price should drop. The launch of Socket M2 motherboards is scheduled for Q2 2006.