I'd have to ask novice - Lap or Hammered dulcimer?

If you're talking about a lap or mountain dulcimer, something like the Korg CA-20 should be fine, and you should find them available in the $15 to $25 (US) price range. There are a few other brands and models, mostly very similar, and you should not have a problem with almost anything available in your area. I have a number of friends using the Korg CA-10 and CA-20.

There are a very few similar looking ones that tune only the "standard guitar" (or violin, etc) notes. I'd recommend you avoid them, and get something that will tune "any note," but if you're aware that they are out there, you shouldn't have a problem avoiding them.

The one mentioned above by Mudlark, at Blue Lion is a decent one, and at a very reasonable price if the shipping charges are acceptable.

If you're talking about a hammered dulcimer, I'd agree with Murray that you should consider getting a somewhat more "sophisticated" model. You've got a lot of strings to tune, and a larger display will help. You'll also find it easier to keep something a little larger "in place" while you're tuning an HD - and the extra bulk won't add much with an instrument this large.

In either case, I'd recommend getting a "clip-on" pickup, as the stronger signal makes any tuner easier to use. The one at Blue Lion is better constructed (based on the picture, at least) than what I've seen recently in my local shops, and is reasonably priced. You should also be able to find something similar in your area shops at about $9 to $25 (US). [You may also find the "vacuum cup" stick-ons, and they can be usable; but tend to fall off when you want them to stick, or stick too tenaciously when you try to take them off (an either-or thing). I avoid them.]

John