In the U.S., some states also sell seedlings and in quantities less than 1000. A few examples (with prices):

New York: https://www.dec.ny.gov/animals/75799.html

Virginia: http://dof.virginia.gov/infopubs/Seedling-Price-Guide_2018-2...

Washington: https://www.dnr.wa.gov/programs-and-services/forest-resource...