If they do need adjusting, you can take them into any optometrist... Sam's Club, VisionWorks, etc. and they will adjust them for you. DS is hard on glasses and has done this many times.You can get a pair of single vision glasses, which I am sure your son wears, for as little as $20.00 from Zenni, which is what I use. Even if you choose to use the Insurance money for a pair at the optician's office, this makes a great spare, at very little cost.
People have told me in the past, yeah, but who will adjust them? Never had a pair that needed adjusting yet after buying probably 10 times.