I ordered the 06-10 Yaris armrest from E-bay. Cost was $35.99 with free shipping.
Installed it yesterday and it is a great addition. You do have to cut the nub off the bottom of the armrest, which I'm assuming is used to anchor is securely in a Yarls. About 2 minutes with a saw took care of that, with a bit of cleanup of the cut with a sharp chisel.
Added some packaging foam that we had laying around from a Harry & David fruit delivery, which was the perfect length to go around the armrest cup holder insert. Cut a round piece for the bottom and in it went.
I haven't decided whether to secure it further with the included screws, as it seems pretty stable as it is. Looks great and provides a needed place for the right elbow to rest.
Nice features include the opening top; removable tray to hold coins, etc.; and a rear fold down cup holder, so you don't lose the one available for the back seat. Even the covering looks and feels like leather (I'm guessing it is some imitation, but is looks nice).
This is a great addition. The fit is near OEM and the price is right.
Packaging was generic, not an official Yaris part apparently, but designed to fit multiple applications.