With the exception of the "within reason" part, I'll have to respectfully disagree. 30 years ago someone spoke your exact words to me, I disagreed then for the reason of being "frugal," I disagree now for another reason.
Back then, being "frugal" I did not see the wisdom of "quality glass!" After the failure of a "Trasco" and a Simmons, I learned to stay away from the low-end scopes!
Now however, I disagree with this because today, most decent gun companies are producing rifles in the 400$ range that are far better than the average shooter is capable of! Some, that shoot on-par with high $$$ rifles.
On the other hand, scopes in the 3-600 $$$ range, are "quality" buys. (By this I mean that your "guns" capability will not be limited by the 3-600$$$ scope! No matter if the gun cost 400$$$ on up!)
Beyond this range, I feel that the "bang for your $$$," falls off sharply!