I'd have to agree with all of the above. I have a proto (engineering build) pf in mine, that I bought in the WMS parts fire sale back in 2000.
Cabinet is in okay-ish condition (game was a Namco operated game), but it's 100% complete.
The PF, of course, is NOS brand new. The only games played on this were at SFGE this past weekend.
If I were to sell it (and no, it's not for sale) I'd sell the cabinet + the installed proto pf, + the original pf.
My price would be minimum 7500, and as much above that as I could get.