Sources for seedlings

Hi, folks, thanks for reading. My garden manager here where I'm working at Emerald Earth is looking for a good source for seedlings of Morus nigra (black mulberry), Robinia ambigua (thornless black locust), and Gleditsia tricanthos (honey locust, preferably also a selected thornless variety).  We want to get a lot of them, so we're looking for a nursery or individual who will sell them for less than $2 each. Does anyone know of a good source, especially in Northern California?

Thanks again for taking the time to share your leads.

can't help you with seedlings, but I believe J.L. Hudson sells seeds of those species.

That's an option; thanks tel. I'll suggest it, although I'm sure she's probably considered the logistics of starting all of them from seeds. I think we're looking at a pretty extensive project for soil restoration and goat forage.

when i started trying to be green as well as being interested in being green, i used to pick up the many seeds of these trees that have been planted in all the central streets of madrid robinja fasle acacia and gledsetia tricanthos  and plant them in pots and they do grow from seed and I can never get bought seeds to grow, so they grow for any duffer.
  I read somewhere that it is better to get a lot of seed if you are collecting seed in case some aren't viable. That is good advice you may look strange in the centre of a big city collecting seed but it is one way of getting it and if you are looking for very cheap seedlings they are likely to be small so seed and very small seedlings cometo the same difference nearly.
    If you give time to going to nursery gardens then you find out who sells what cheap where. One nursery garden i go to has lots of different prices for its trees, it all depends on how big they are what they cost. they don't always have all sizes in stock.
  If you are looking for nitrogen producing plants brooms and gorses are also nitrogen producing i presume, they are leguminosos. agri rose macaskie.