The King's Castle in 1985 cost $43 for 664 pcs. That's $122 in 2021 dollars.
Lego Hogsmeade Village (Harry Potter) costs $80 on Amazon right now for 851 pcs
The 427 pc Galaxy Commander Set was also $43 in 1985 so, again $122 in adjusted dollars. Guess you weren't exactly paying per piece.
That and some more lazy browsing leads me to believe that Legos are less expensive these days. But this has nothing much to do with what someone's parents were making those days. For one thing, housing costs, education and medical were much lower so you could be significantly poorer in raw adjusted income and still have more money to put towards Christmas. Also, people tended to throw away or garage sale more stuff then as opposed to people being convinced that their storage box of Legos is a retirement fund so someone could collect a bunch of random mixed Legos for cheap/free.
(Also, I'm basing this off sets I remember from way back when. If you're some dirty Millennial kid, go find your own Sears Wishbook archives)