I just got some Java Moss grown on black slate for $7 on eBay (that includes shipping). I know he has more for sale. My package should arrive sometime tomorrow or Friday. I can let you know how it goes.
This is my first eBay plant purchase. I hope it goes well. I tried to get some Hornwort on AquaBids and it did not go well.
Bradbury - VT
R.I.P Neil - HM