I can't confirm those season pass prices or deny it, although i want to strongly deny that, but my memory is faded. back then day lift tickets were so cheap.. I worked there in 1990.. what i can confirm through the 80's and leading into the 90's is $10 mon-tues and $15 wed-thur-friday day tickets at many WA. resorts or something very close to this.. I doubt shitty pass ever came close to 1k for season passes, ever.. I can confirm a Mt baker season pass for $500 in 1995 which was one of the 1st season passes I had bought...
after some digging..
what i did find was North Cascade Heli $325 for a day in 1990.. which is now $985 for a day
1990 Wa. breakdown
Sports | Washington Ski Areas | Seattle Times Newspaper