I think I've gone over this before in another thread, but here's a little trick that often works:
After exhuasting all the nice-guy methods, hire a lawyer just to right a letter demanding payment, and have him send it on his letterhead. My guy does it for $75, and I'd say about 8 in 10 have at least started communicating back to me and arranged payment, if even in installments.
If that doesn't work, and you aren't eligible for a lien, it's time to consider litigation. It's rarely worth the headache if it's not less than $5000 (small claims - no lawyer needed) or over $10,000 (this will usually be widdled down for a settlement before it goes to trial, and you should always add the legal fees on top of it).
It sucks, and it's a big waste of time, but a small business can easily get killed by an unpaid bill.
I don't get the problem, I always pay MY bills...
