Max if you were closer I could turn you on to some Walnut I milled few years ago, got couple hundred ft waiting for a future project or whatever. I milled several chunks 3" and 4" thick for gunstock or bowl stuff. Not sure I would call our woods "exotic" but the Appalachian woods running from New England down through Georgia do have more different species/acre than anywhere west of the Mississippi. Only certain pockets of Florida (tropical) have more species. As for growing Walnut up where you are, keep in mind that Walnut, like Black Cherry is a species that needs good rich soil like that which you find in bottom-land to grow well. That's why you rarely see a (naturally growing) Walnut or Cherry tree on a rocky slope or near top of a mountain. Soil is usually not good enough for them. I've seen them growing in sandy soil in NJ and Md, but it has to be "good" sandy soil, mixed with peat, dirt and well drained. If you play your cards right you can get trees to grow where they don't naturally, but they'll rarely do well without constant nursing.
Dave