Man, I remember when #75 (the death issue, black polybag) came out. Idiot who owned an LCS back then speculated the damn price of that book to $75 by the day the book came out. The backlash, rightfully so IMO, put him out of business. If that thing is worth $150 in mint condition (9.8) I would be shocked. The white bagged (Adventures of Superman #500) is worth less.
I have the black bag, as well. I believe they printed those things into the ground, though, so they're not exactly scarce. For me, they aren't about the money. It just brings me back to a time before I had much to worry about.