Artifact Puzzles can be bought in person at: 

Cat and Mouse Games in Chicago

Games People Play in Boston

Seattle Art Museum Gift Shop in Seattle 

Northwest Fine Woodworking in Seattle 

I'm Puzzled (Puzzle Specialty Shop) in Pacific Grove, California (Monterey/Carmel area)

I'm Puzzled (Puzzle and Lobster Shop) in Waldeboro, Maine (between Portland and Bangor)

The Missing Peace (Puzzle Specialty Shop) in Lambertville, New Jersey (between Allentown and Trenton) 

Hill Museum and Manuscript Library Gift Shop at Saint John's University in Collegeville, Minnesota (near St. Cloud)