Those of you with a love for exotic instruments will either love me or hate me for sharing this link: http://www.larkinam.com/
Hammered Dulcimers aren't that hard to come by though; I got mine on ebay for $50 or so about 5 years back (needs to be restrung though). There are a few players in the Celtic scene around here. Most of them built their own.
The instrument I've always wanted, but never have been able to afford is the Hurdy Gurdy. Awesome instrument, but not cheap!