The clothier buys (and sells) most non-armour items which are worn, including robes, smoking jackets, fancy dresses, hats and jewelry. The Dwarven armorer buys most non-magical armour and simple mechanical devices (other than guns). Which is why I'm surprised that neither would spring for a tech-based ring.
You can 'force' anyone to buy anything, and at their going rate (much better than the junk dealer) by investing in Haggle expertise: it requires at least 2-1/4 ranks in Haggle (which means having 12 WP plus three character points; unless you're a Gnome or have some other appropriate background, in which case you can do it with 9 WP plus two points). Apprenticeship is found via shopkeepers and herbalists, and expertise from any bartender.
I love Haggle so much because I'm a soloist at heart; it saves me the aggravation of having to drag someone around just to be a pack mule.
Speak softly, and carry a big stick. Or better yet: a big, sharp blade