It was major news in 1965 when ON A CLEAR DAY... started charging $11 for Saturday night seats.
From OKLAHOMA! (1943) through HELLO DOLLY! (1964) the top ticket doubled from $4.80 to $9.60. (That's over 20 years.)
By the time CHORUS LINE came along in 1975 it was $15.
Liza Minnelli's THE ACT (1977) was asking for (and getting) $25
42ND STREET went to $35 (with house seats offered for $50..David Merrick assured us it was just to thwart scalpers.)
With a few years the top ticket jumped to $45 (1984) $47.50 (1987) and $50 (1988.) Then JEROME ROBBINS' BROADWAY came in asking for $55 in 1989.
By 1994 SHOW BOAT came in with a $70 ticket while the awful SUNSET BLVD got away with $75.
By the century's end $90 was the regular top. THE PRODUCERS opened with a $95 but soon took it to $99 with the best seasts in the house going for $480!
We thought they had reached their max when teh $100 ticket became the norm but now most shows charge $120. (No wonder people on here are always asking for discount codes and deals!)
To put it in perspective a top seat to OKLAHOMA! in 1943 cost about the same as the original cast album (on 6 10-inch records.) Today a cast album costs $20 and a ticket to the show is 6 X that.
Cast albums are NOT "soundtracks."
Live theatre does not use a "soundtrack." If it did, it wouldn't be live theatre!
I host a weekly one-hour radio program featuring cast album selections as well as songs by cabaret, jazz and theatre artists. The program, FRONT ROW CENTRE is heard Sundays 9 to 10 am and also Saturdays from 8 to 9 am (eastern times) on www.proudfm.com