I'm not sure there's enough information for a good estimate on that scale. For example, 1500 pop bumper assemblies would be a considerable different number, assuming your hypothetical table only had one, than 4500 assemblies for the same table if it had 3. Factor in additional costs of multi-level pfs (with associated metal work) as well as other unique features (special function toys), and its really not a simple question of how much to build 1500 ambiguous pinball machines.

Perhaps if you provided an example table (with commentary on any differences), figures for the 1K -1.5K volume could be better estimated.