Specifically, Bethesda will no longer manufacture real life Pip-Boys for future retail. Bethesda's VP of Marketing and PR Pete Hines took to Twitter and briefly stated: "Each store is being given their final allotment. How and when they make the[sic] available is up to them. but no more are being made."
If you missed out on the first and second rounds of pre-orders, it seems like you're out of luck. Whatever's left in stock during launch day on November 10, 2015 will likely be the last batch of $120 (£99, about AU$155) special edition Pip-Boy bundles.