On History: Inflate-O-Spidey
I also seem to recall that they were reasonably priced. Almost to the point where I could've afforded one, despite not having a job at the time. I want to say they were $100? But I had no way of getting one, since I didn't have any retailer connections at the time. There was effectively no after-market for these because none of the retailers who did buy them wanted to part with them.
Decades later, they're available on ebay with some regularity. I see two that still come with the original box at the moment. But despite having the funds to purchase one now (they still seem to only be around $100!) I find that there are so many volumes more of commercially available products that are better displays of a wider variety of comic book characters, that the inflateable Spider-Man seems pretty chinsy by comparison. It was essentially made in the last days of Marvel just starting to make it big time, but just before they really developed the savvy to do really quality marketing. It's a large tchotchke, not appreciable any different than a logo-emblazened bag or stress ball.
The key to tagging this to a period before they started doing quality marketing is that some of the folks at Marvel sat down in a room and decidedly, jointly, that calling this "Inflate-O-Spidey" was a good idea.