So basically I want to build a game , I also wanna learn the process with basic earnings pre release .I am not aware of anyone who had such experience or anywhere near it.
As all professions and jobs in life, it depends. You cannot spend one week/month to make a simple game and expect thousands of dollars. To stay on topic, my latest project where i managed and produced a 2d game, cost me around half a grand and i am in process of selling for few hundreds more. There are different methods to consider, like ads or self-launch, so it depends what platform and targets you aim at, or better said the type of game you work on.
You should share your game or plan of your gig. Good luck!