A new Yucca Schottii found under Decor / Plants, costs 0. You need Ambitions and to place the package in both the mods/packages (Sims3 ) directory and in the "The Sims 3 Create a World Tool/ Packages" directory for the item to show in your game. There is an earlier post explaining how to install items in CAW.
Importing packages into CAW
You can just place it in any lot if you don't want to use it in CAW.
Yucca Schottii (MediaFire)