Key takeaway from the above: your contract terms matter enormously. The copyright retention clause was the real leverage here. If you're a freelancer without one, add this to every contract:
"All intellectual property rights in the Work Product shall remain with [Freelancer] until full payment is received, at which point rights transfer to Client."
Other protective clauses: (1) late payment penalties (1.5%/month is standard), (2) right to halt work for non-payment, (3) attorney fee shifting clause (loser pays winner's fees — this deters frivolous defenses), (4) kill fee for cancelled projects (typically 25-50% of remaining value).
For amounts under $10K, small claims is almost always the right venue. Fast, cheap, no attorney needed, and judges are sympathetic to contractors who completed the work.