I have often seen potted plants, trees and "you dig" trees for sale on Craigslist. I think they come from people who change their mind (and the plant is still in the pot), change their landscape, never get around to planting, or know how to root cuttings.

I also see plants for sale at the local flea markets and green markets.

Lastly, they are often for sale at yard sales/garage sales.

Carol in Jacksonville

Here is a link that might be useful: Craigslist - Florida cities

Rare palms and the occasional rare tree will spark someone's interest. A Java Plum is a very common and very high maintenance tree. If you want to get rid of it, just chop it down and haul the pieces to the city dump.