I heard one of my friends said that he was charged $60 at OPSM on Queen St. But i saw their sites shows that you can also get some awesome deals if you use these coupons though. Maybe you can have a try. And i also find their phone number at their sites: Calling 13 20 20 (AUS)
Calling 0800 696 776 (NZ)
Maybe this helps if you want to get further information about them.
My friend had the eye test last year at opsm. She was charged $60. You'd better prepare more than that money in case of the increasing price. However, you can wait for its discount activity. Maybe there will be the activity that buying the eyeglasses or the contact lenses may offer the free eye test. And you can call their store and ask the exact price and service.