What you don't seem to understand is that the mite issue is not so simple. You have most of this forum telling you it is NOT a good idea to purchase a snake with mites... that it is NOT a simple issue. We love positives here, we really do, but all the positives in this case are negated by the mites. Shouldn't that tell you something?
The snake looks healthy... GREAT! Seriously, good to hear! But if it has mites, the possibility of it being unhealthy is much greater... snakes are creatures that don't show symptoms of illness until it's practically life-threatening, or already too late.
If you're bound and determined to get a snake you can see first, I would wait until you find one with no mites. Most everyone else is recommending the same thing. Doesn't that tell you something???