Ebay, you can almost find everything you want there, and for most seeds it's cheap!
http://www.ebay.com/sch/i.html?_odkw=American+elderberry&_from=R40&_osacat=0amp;_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.XAmerican+elderberry+seeds&_nkw=American+elderberry+seeds&_sacat=0

magg_ca
it grows wild here.
i have several small ones and seeds
black variety (wild)
anything to trade ?

The New Hampshire State Nursery sells them Cheap.

Here is a link that might be useful: New Hampshire State Nursery

They grow wild at my place, too, and I would love to trade.

I got 4 different commercial type elderberries from the Botany shop in Joplin MO last year. They were very reasonably priced for small plants, 2-4 dollars each, and grew between 2 and three feet over the summer. I didn't lose a one and they are alive this spring. Here is a link to the site: botany shop