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In the U.S. you can get one from Tesla installed for about US$1500 (I don't know about Hong Kong), or get an after-market one for a lot less and install it yourself. See: Carbon Fiber Spoiler
If you read the CF Spoiler thread above, my theory is that all of these 3rd party, after-market spoilers all come from the one or two factories in China. And if that's true, then yes, many of us have installed these spoilers (see aforementioned thread).
Just telling that ANY spoiler will reduce the range. The bigger the spoiler the more it creates drag.
Even OEM spoiler has some negative effect. Though it is extremely small.