I just bought a 2007 9-5 with only one key. A replacement from the dealer will cost $250, which seems excessive. Will a key from another 2007 Saab work for all the parts but the engraved part? Who might have a salvage key?
$250 is a good deal. My local SAAB guy quoted my girlfriend $300 for another key with the clicker built in for her '00. She ended up going with just the key @ $70 and a used fob for $20 programmed to her car.
I forgot to answer your original questions - you can re-program remotes from another car, but if you just buy a key it won't work till it's mated to your car (and you have a blade cut correctly to turn the lock cylinders of course).