I agree with Qwiks on that too, walk away quickly if they want extra to order it, if it's not even going into their inventory and it's presold why would they want more? Some will ask for a deposit just to guarantee that you actually buy it but with a relatively brisk seller like the PT145 that shouldn't even be the case.
Layaway is a great thing too!
Oh yeah, another good way to see the appox manuf. date of a gun is to look at the test fire casing envelope in the box, it'll be signed and dated (can't remember if my 145 came with one though).
Good luck and safe shooting!