Everything about this hobby has increased in expense over the years, however the quality of kits and aftermarket has gone up too. Still, I just paid 6 bucks for a can of Testors spray paint. I go into my local shop to get 4 bottles of Tamiya paint and walk out $20 lighter.
Styrene kits are still much less money for the most part than scale trains. I used to be big into HO scale trains, still have a nice collection, but I can't keep up. People will pay crazy money for plastic locomotives with DCC, electronic decoders, etc... I don't keep up with it anymore.