I think people have mentioned this, but I haven't seen an answer: why not ask friends and neighbours? That's what I do, and I've had success with it (though I'm more frequently the person that neighbours and friends ask for professional contacts). When no one knows of anyone, you search and call people and evaluate/assess. It's not _easy_, but it doesn't seem like such a big problem.

Am I missing something, here? Is your device something that only 100 people in the world know about? :D