Looking to buy some seafoam

I've seen and heard plenty on this "seafoam" material for making trees.  The problem is, I've only found one or two websites that sell it, and they all try and sell you a giant box of the stuff, for planting giant railroad layouts, not to mention that that's just the base, you still need to buy additional foliage and such.  I only need a few sprigs/stems of it for making a couple trees, and testing it out before I buy a bunch.  If anyone has some extra, I would be willing to pay plenty for it.  I'd also be interested if anyone know of websites that sell just a little bit of the stuff, so I don't have to spend tons. I'm going to check my local railroad shop, but I don't have high hopes, they usually don't have a ton of stuff.  Thanks, Ian