This place: http://www.pacificcoastwoods.net/ukelele.html
The myrtle for my baritone came from there. You can't go just by the website though. If you have something specific in mind, send an email and they can send you pics of sets they have in stock.
lol...Saw this thread..."Anyone-know-good-places-to-be-unusual" and thought I'd weigh in that, in my experience, NYC was a good place or just about anywhere in Cali. Don't know diddly about tonewoods.