Amazon just dropped their price to $169.99 so I preordered not that I wasn't going to anyways :D
I expect it to be down to somewhere between $129.99 to $149.99 by release date.
Lots of sequels were not common back then. I think they figured they had run the course with Godzilla after the 1st two films. Toho released lots of other sci fi and Kaju films in that 8 year gap: Rodan (1956), The Mysterians (1957), Varan the unbelievable (1958), The H-Man (1959), Battle in...