We have a mottled cream one in our collection

That radio is worth about $6,000.00 as the marbling is very significant and symmetrical, providing the cabinet has no damage.

I was under the impression the green one was a one off prototype?

It depends on the green you speak of.

The more common jade and soapy green versions were made in reasonable numbers (several hundred I'd say) and around ten to twenty are known to survive in good condition. The weak point is the knobs and many a good cabinet is unfortunately partnered with cracked knobs.

There is one mottled green (more a peppermint colour than green) cabinet known to exist with matching knobs and in good condition. It is rumoured (and only rumoured) that the lucky owner of this set has knocked back offers in the tens of thousands for it and in reality, why wouldn't he? A radio is ultimately worth what someone will be prepared to pay though only for that transaction. Whoever does eventually offer enough for it will never get his money back when it is on-sold but will have the privilege of owning something that is unique and genuine.

There are also rumours (and again, only rumours) that navy blue and fire engine red Radiolettes exist in South Australia. I think this can be taken with a grain of salt though. I've never seen one in over 26 years of collecting and never even seen a photo of one. I cabinets exist in these colours I would at this point in time suggest they are replicas and not made by AWA.