I was thinking about that, but don't have access to the inflation data. However, anecdotally, I bought my first season ticket for the 84/85 season. I was a student, but had to buy a full price ticket as we didn't have students' concessions in those days. I was working a summer job at the M74 Services in Strathclyde Park, so spent some of my hard earned.
The season ticket cost me 32 quid with the early-bird discount. That ticket gave me entry to every home league game, every home cup game and every reserve game. I don't recall the exact gate price at the time, but I do remember that the season ticket saved me over 40% on league and cup games. We may have got pre-season friendlies on it too, but I may be misremembering that.
I'm pretty sure prices have risen faster than inflation, but even if they haven't, I got a lot more value from a season ticket in 84/85 than I get now. So that alone makes the game more expensive.