NVIS form / Bill of Sale

I bought a scooter on the weekend - 2007 Derbi. The scooter was never ridden and only has 17 km on it. The seller does not have the original bill of sale from Motoretta. Now, what do I need to get it registered? NVIS form? Is Motoretta going to want a whack of cash to produce this form?
Any other solutions? Thanks in advance.

If it is to be licensed you can take the serial number to the MOT and get a UVIP that will show the present registration status. Was it hot or not.