Very useful and a bit scary thread! For the replacement/new item (PEM/battery) discussion, the information below from Tesla Motors (sent late 2011) might be useful:
"The cost of the US PEM would be $16,713.48USD. Upon receiving your old PEM back, we would proceed to refund you half of the funds as a core return. The PEM would have to be in good condition, repairable, and not damaged in any way by shipping or outside influences. The warranty label/seal would also have to be intact upon receipt. Upon receipt of your old PEM in good condition, we would credit you $8,356.74USD. "
That is without labor to install, but from watching the Techs it is about a 30 minute job to swap out PEM's.