Suggest you look at village houses in Tai Po. We live on Ting Kok Road about 12 min from the KCR line, which is an easy ride into Kowloon plus there are buses going to Mongkok, Jordan, etc. We bought our house but have seen 2 floors with garden or rooftop renting last year for $12K - 20K right near bus stops and some with sea view.
I love Tai Po and it's a fantastic place for a family if you like doing things outdoors. There is an aquatic centre and public pool down the road plus Tai Po itself is one of HK's largest cities. We have both big stores like Jusco and Park N' Shop Superstore along with lots of local vendors so prices are much lower than elsewhere in HK. In good weather I ride my bike grocery shopping all over, which is something you cannot do anywhere else in HK. Heard there are decent schools around but you have to ask someone else for that info.
Go to the realtors in tai Po itself and also to the agents in Tai Mei Tuk. Happy house hunting!