Check with your state forestry service. Here in KY we can buy seedlings of just about any native tree in the state. We can get 500 seedlings for about $80.00, or 50 for $15.00. Just abut all states offer this I think.
Good Luck,
Here' s the link for your state to buy seedlings.
http://www.dnr.state.mn.us/forestry/.../ordering.html