The original M1 (I assume that's what GP meant by "at launch") uses LPDDR4x DRAM modules, the same as many x86 laptops that have soldered RAM. You can literally look up the part numbers based on the photos of the M1 CPU package. Maybe I'm misunderstanding but I'm not sure why it would be any more expensive than x86 laptops' memory, and it might even be less expensive just due to the volume that Apple is likely buying.
