Most States have a State Nursery but NC and SC are pretty lame. Iowa's got a good one as does Missouri where I live. Some will ship out of State. I can get 2 year elderberry seedlings for 40 cents a piece from MO but they only take orders in the fall and run out quick. Iowa has most stuff still in stock.
http://nursery.iowadnr.gov/Elderberry_p_167.html
I've gone most of the way through the checkout process and unlike a lot of the State nurseries, they didn't require me to choose what county in that State I'd be planting them in. I'm not ready to buy. I was just checking out what they had and was curious to see how the checkout would go. They don't say how old the seedling are. They go by height. 11-20 inches is 65 cents and 21-30 are 90 cents. 10 bucks shipping. They also
sell 4-10 inch for 40 cents but they're out of stock on that size. Everything's sold in groups of 25 so if you do qty 1, it's 25 and that's reflected in the cart/checkout.