Well off the topic, I never buy plates outside the dealer. Make my car look like a used second hand car or those grey imports.
650 for a pair seem expensive to do it outside, but to each their own.
Edit: 650 is for those 3D letter type didn't realize that. But the market price for those should be 600 if you do it at those shops in Kowloon City. I guess that's the price you paid for sitting in the comfort of your own home.