Without saying anything about this particular situation, can I just point out for the four hundredth time that $780 invoices generate far, far, far more stupidity than $7,800 or $78,000 invoices do?Your argument is a classic case of the correlation/causation fallacy.
A modest invoice does not "generate" stupidity. Millions of freelancers around the world make a good living doing relatively small jobs for satisfied customers and submitting modest invoices that get paid on time.
If you are in a position to work on higher-value deals, then naturally you will be dealing with other people of the same level. To get to that level typically requires a certain degree of professionalism, whichever side of the deal you're on. So sure, people working with higher-value contracts tend to have less hassle.
But being messed around by someone who won't pay your invoice doesn't mysteriously become your fault just because the invoice amount was under $1,000. That really is akin to saying that it's your fault you were robbed because you forgot to lock your home, or that she was asking for it because she was wearing a short skirt and had a couple of drinks.
Many of you will be able to pick whether you are either of these types of people. I suggest being neither.
I usually agree with your comments, but in this case, I'm afraid your advice is like saying "Make sure you run a successful business and deal only with great clients!" If it were that easy, everyone would be doing it. In reality, even those of us who are successful today were the new guy once, and I expect that almost all of us have made at least one deal we would have preferred to avoid, so that we could pay the rent or fund a side project.