Another thought provoking topic Arnold! Thank you!
Since 75% of what I own I bought used at shows, hobby shops, action sites, and making trades, I've never spent more than $400 for a single locomotive which I guess is "big bucks" for me. Paying $1000. plus for a locomotives is something I could never feel comfortable doing, however, that's just me. Folks who feel comfortable doing so, I say " go for it!"
As I model the transition era, I have little interest in modern locomotives and rolling stock both real and model. Today as I took my house quest back to the MARC station I saw the Acela whiz by on the express track at speed. Although my house quest found the Acela exciting, for me it was like drinking a flat Coke .. no fizz. On the other - hand, when I hear the rev of a EMD 567 prime mover or the hiss of steam from a steam locomotive my pulse quickens and I get butterflies in my stomach.
In view of the above, after being back in the hobby for 20 years, I now own all the locomotives of the transition era that I have ever desired ... from electrics to diesel to steam. The same with rolling stock. Of course I have learned to " never say never". I'm sure going forward, there will be a piece here and there which will capture my fancy and therefore my dollars.
Any monetary investment I make in my layout now will be modest. I have plans for a small yard which should not cost all that much due to the fact that I already have the track and perhaps the switches to do so.