I guess it depends on what you mean by "original screenused".
Seriously tho, I believe it is impossible to prove at this stage, whether a particular prop claimed as "screenused" was actually used on the show, or not.
But the most recent "claimed to be screenused" phaser one (a dummy hand-phaser prop) was in Profiles in History awhile back, and is now located in the Seattle Science Fiction museum. I don't recall what it sold for.