For perception of cost, I think the "threshold" is more important than the inflation. As others have said, it matters what you can afford (or think you can afford). Circa 1980, when I got the 1st ed. AD&D PHB, MM, and DMG as gifts, you could get them from the Sears catalog for $10 ($12 for DMG). For my parents, living within 10 miles of work, $10 was a month of gasoline, even driving an old gas guzzler. I didn't play Runequest or other things that interested me--because I could afford one gaming system.
I don't remember what I paid for the 1st ed. Fantasy Hero in 1986, but it was equally hefty for the time, and I didn't blink, despite being in college, and having to live off what I made in the summer. A threshold got crossed. I couldn't just buy every book in the store, but if I really wanted a game, I could get it. I do remember that I bought a computer game for $55, that was pushing it as bad as that $12 for the DMG was earlier.
The clearest example of perception of value that I have lived, however, has been with food. I lived in Connecticut for two years in the early 90's. This was a shock for someone from the South. My wife and I enjoy eating out. In Connecticut, due to no tax on food, but high cost of living for everyone preparing the food, there was a huge jump in what we were paying before we moved, for essentially the same quality of preparation and service. But in Connecticut, you got a lot more food. It simply wasn't economical to sell what we considered a "normal" portion. (Big portions have long since become nationwide, but at the time it was a shock.) As $/unit of equivalent food, CT and AL were roughly equal. If you wanted lots of food, CT was superior. If you wanted less, AL was superior. (If you wanted good BBQ, there was no comparison ... but I digress.
)
If you could make the three core 4E gaming books, with half of the most popular/important content in each, and sell it for half price, you'd sell them like hot-cakes, and a lot of lower income people wouldn't have their threshold passed. Unfortunately, such books would need to be a lot more than half price to be profitable.