Yep, the Sydney and Melbourne Bintel Stores are the only 2 authorised Televue Dealers in Oz. That info is actually listed on Televues website.
Some O/Seas dealers will ship TV eyepieces to Australia, but it's in breach of their Televue distribution agreement so none of them advertise the fact. Also if you did have a warranty claim things could get complicated
I would stick with Bintel and ask them for a bit of a discount as in IIS referred customer.
CS-John B