As stated, I don't think $700 is at all expensive for a Michelin 2* or 3* restaurant. That's actually cheaper than in most other parts of the world. Keep in mind there are 1* and other good restaurants in HK for less than that, and I'm not just talking Tim Ho Wan. If you're talking truly "fine dining", there's no reason for HK to be cheaper than other cities because their clientele is just as rich and their staff are just as well paid.

If you really want a "cheap" 3* dining experience, the Waterside Inn (<1h outside London) is probably better value than anything you'll find in HK.