If they're high-end lenses, you might find a compatible back. If the cost is an issue, many places like B&H sell [link|http://www.bhphotovideo.com/bnh/controller/home?O=UsedHomePage.jsp&A=FetchChildren&Q=&ci=2872|used digital equipment].
Let's see, you've got a Nikon [link|http://z.iwethey.org/forums/render/content/show?contentid=277234|F60]. (I'm assuming the F70 is similar here.) It looks like your lenses [link|http://photo.net/bboard/q-and-a-fetch-msg?msg_id=00EYZ9&tag=|should work with the D70], with some caveats (check the comments). B&H has a used D70 back for [link|http://www.bhphotovideo.com/bnh/controller/home?O=2891&A=details&Q=&sku=800517109&is=USE&addedTroughType=categoryNavigation|$449]. Presumably there are places in Oz that would have comparable deals.
HTH a bit. Good luck!
Cheers,
Scott.