Can I build a $400 gaming PC? Or cheaper?

Alright so soon, if I play my cards right, I will be able to earn about $500 and I want to spend it on a gaming pc with some money left over. (

Some games the computer needs to be able to play: Counter Strike: Source, Counter Strike: Global Offensive, league of legends, minecraft (with/without mods), Fallout 3, The Walking Dead Game by tell tale games, and GTA 4

Please note I already have a mouse a keyboard, and a monitor.

Well, in conclusion, because it's impossible to build a gaming pc for less than 450 at least!

Here is MY best recommendation for you:

He spent 450$

You are not going to be able to create anything special for that price. You are going to need around $550 to $600 in order to create a base line gaming computer! I'm sorry to burst your bubble, but you could start buying parts and picking up odd jobs to make a little extra money! I wish you the best of luck in your adventures!