Hi,
Why bother building one yourself unless you need more dramas in your life?. I have a nephew who has a degree in computer science whatever that is and he was clueless when I asked him to see if he could sort out some problems I had with my el cheapo cctv system.
I ended up sorting out the problem myself (faulty power adaptor). CCTV is becoming cheaper by the day and you don't need to be a rocket scientist to set one up especially if you are handy with computers. Just my experience