Thanks for your input ladies and gents!
Here are a few more pics of those plumies:
I couldn't get a hold of the nursery staff at the phone, to ask about the nursery/grower they are getting them from. I left a message and then somebody called me back and left a message with completely different info than I needed. So, per their message, prices are:
1 gallon - $19.99
5 gallon - $49.99 (I guess the Hawaiian Gardens was something special at that price)
15 gallon - $119.99
And they have 50-60 5-gallon plumies there now.
I'll try to find out if they grow them or where do they order them from.