I'd say it's all about checking out a few key things. I've found that reliable ones are upfront about their products and quick to respond to any questions—if they're cagey or avoid details, that's usually a bad sign. One place I trust for unique pieces is
smokeday.com. They've got a cool selection, and I've always had good experiences with quality and delivery. Also, looking through reviews can really save you a headache; if others have had issues, they'll usually make it known.