We've been living in Sai Kung for two and a half years now and we love it here. There are a lot of expats and since Sai Kung used to be a fishing community, there are also a lot of locals. There are a number of facilities in Sai Kung town that won’t cost you an arm and a leg to enjoy, e.g. sports ground (track/soccer pitch), pool, public library, squash courts, tennis courts, many playgrounds, and some really good restaurants and bakeries! There are a few marinas and sailing clubs in the area as well, not to mention, Sai Kung is just a short distance from Sai Kung Country Park and Ma On Shan Country Park. We are also just a short ferry ride to some of the best beaches in HK.
The arrangements of the houses in some of the villages are not as well organized as DB, but there are areas where the houses/flats are very well planned and have full facilities (pool, gym, club house, etc.) With your budget, you could probably get a 3-storey house with a garden.
We don't have a car (yet), and we think the transport arrangement in Sai Kung is not so bad - the minibuses are very frequent and they can take you to the MTR stations (Choi Hung or Hang Hau Stations) or straight to Mong Kok, which is the heart of Kowloon. There are also buses that can take you into Kowloon, and other parts of the New Territories (Ma On Shan/Shatin) or the country parks. However, if you live inside the country park, or some of the remote villages, then having a car is definitely a plus.
My husband works at the airport (shift work) and we have quite a few friends who are either pilots or aircraft engineers and live in SK. For my husband, he travels to work by minibus (to Choi Hung) and then the airport bus; it takes him 1.5 hrs to go to work. For him, he doesn't mind the travelling as he really likes Sai Kung and likes to spend his off duty days in SK (a very relaxed part of HK and close to nature). Also, I'm not sure about DB, but he said that the air quality in Tung Chun/Airport is not very good and he would rather live far away from the area.
Not sure how long you’ll be staying in HK and the schooling you plan to give your child, there are some good English playgroups and kindergartens here that have students entering ESF schools, and international schools. There is an ESF kindergarten and a primary school in Clearwater Bay and a through train ESF School (Primary to Secondary – Renaissance School) in Ma On Shan.
Anyway, I hope this gives you an idea of what Sai Kung is like. Here are two websites if you want more information on SK:
www.exploresaikung.com www.travelinsaikung.org.hk