I agree with Shay, that Walter, wanting to do anything to invest in
that liquor store, relates to Prometheus, who would do anything to
help man. On the other hand, I think there is a large difference, that
Prometheus had others in mind while Walter has only himself in mind.
This makes me think the allusion may be hinting that Walter relates to
Prometheus in another way. Prometheus, once trapped from Zeus’s
punishment, relied on someone else’s help. He needed Hercules to be
rescued. Walter’s lousy job and struggle to bring in enough money for
his family ends up demonstrating his dependence on Mama. He thinks
only her and her check can save him from everything he’s trapped in. I
do think, however, that this allusion to Prometheus is flexible and
many different interpretations can be considered right, as it doesn’t
get any more specific than “Goodnight, Prometheus”.