What suggestions does the seller have ? If it were me - I'd try this mob;

http://www.packsend.com.au/packandsend_int_freight.php

They actually have a box which is the correct dimensions for a playfield. They fill the box up with foam and drop the playfield in, then do the same for the top. It is a "Custom fit". I'm not sure if they have an office in the USA. They are cheaper than UPS.

Thanks Nino (for the 100th time this week  )

Will call the guy in the US on Monday and see what he can do from his end. Then will call Pack and Send and see if they can help.

I still figure that the playfield is only US$75 and if shipping costs me US$150 I'm still doing well 

Well you pinball junkies know how this goes - if you need the part and she isn't available anywhere else you just pay what it costs to get it here