navigation DVD for Maserati

[lilas]

I was wondering if anyone knew how I could get a navigation DVD on New Zealand for a Maserati Granturismo (2010/11). I have just emigrated to NZ and taken my car with me. I did approach the local Maserati dealership and they were quite unhelpful and suggested I pay some ridiculous sum for a DVD.
In the Granturismo the DVD loads the software to a hard drive so once loaded the disc should no longer be required - I wonder if I could borrow/buy a disc from someone or if anyone had any other ideas?
Thanks