buying/selling domains

Hello,
I am new here and am looking to start buying/selling domains. I have a few questions. Are people very successful at this/or able to make a living solely on buying and selling. Secondly, if you sale domains, what is the biggest profit you made? Is this basically based on luck, hoping someone will need your specific domain name. Lastly, where can you buy domains cheap?

I have never done and have a few domains to sell. As I am a bit busy to manage it.

dtraders.info
dtraderss.com

I wont take less than 5$ for each. as those get visitors and also get indexed faster by google.
If you make a website on it, google will index yours as soon as it completely removes the existing website from its index. Can take about 2 weeks to complete.