Everyone here has got some good advice about how to approach buying your son a new guitar. But I'll tell you my story 'bout my first bass guitar.
When I decided I wanted to learn to play the bass at the tender age of 15 years old I insisted that my Dad NOT buy me the bass, but, loan me the money and I'd sign a note to repay him to buy what I thought I needed.
I knew in my heart that if I ended up with some cheap low-end instrument that I might loose interest and be defiled by some guitar unworthy of my talent.
My Dad agreed and I ended up with a Maple finished white trim Rickenbacker 4001 fitted with a bad *** bridge, which in 1984 was $861.64. Top dollar in those days.
Not only that, I am left handed,
South Paw Guitars so my bass had to be hand made and special ordered just for me by the manufacturer.
Years later after playing multiple guitars, did I realize how fortunate I was to have the benefit of learning on a quality professional instrument.
There are many factors that set cheap guitars apart from quality guitars.
As for me, the main factor was whats called action. Action is the distance between the string and the fret bar or fret board. The better the action, the better the speed and clarity in your playing...
...but I ramble.
I think you need to have your son do some research and bring it to you to justify how much you are about to spend.
The more you spend, the better the results.
It's kinda like buying a car, the more you spend on a car the faster and more safely you navigate traffic.
If your son has music in his heart you will never regret your investment.
To answer your concern about living in po-dunk and not having guitar teachers on every corner, you obviously have an internet connection and should be able to find top notch guitar teachers right at your finger tips.
If you feel confused just tell your son to take flying lessons.
Happy Holidays
