Depends on what your definition of a pre-production WL wants to be. There have been a bevy of them popping up on popular auction sites and handed out at various diecast events. 4 or 5 years ago the red test shots and pre-pros were rare and you had to know someone to get one. Now they can be had for relatively small amounts of money.
There has also been some threads that the pre-pros showing up are nothing more than an underpaid assembly line worker constructing his own "one of a kind" pre-pros and selling for a nice profit.
Regradless, I own some and if they are legit or not really does not matter to me. I like them and am happy with what I have paid. Bottom line it is worth what you or someone else is willing to pay.