In , "Dan J.S."
empowered us with this mighty blow against the Patriarchy:

I have spent waayyy too much time at aquabid, and got outbid each
time. So now I just want to buy some plain ol' java fern. What is the
best place to get some?

Unless you can find an online store without a minimum order requirement
(and I'm not saying you can't ;-), your best bet would be an LFS. Even my
local PetSmart sells java fern.