What can I get for <300$

I've built 2 computers so far (mine and a friend of mine) both of which i've picked out the parts because they were mid to high range PCs. My brother wants a PC for Christmas (there's a big age difference between us) and my mom has asked me to build him one, budget is 300$. I've already talked to him about it and i've told you everything that I know. I just want some help from you guys because i've never looked into the low-end of computer building and I would rather not screw up everything for his Christmas (he isn't going to get much else because this a big gift). I asked around /r/buildapc first and i've only gotten one response, this was his build.

Specifications/Side notes

-300$ budget using USD, retailer doesn't matter at all.

-Mouse, keyboard, & headphones, covered, need a monitor,

-It's for gaming, Overclocking would be preferred because it is a 300$ PC, no custom watercooling,

-Have the OS already.

-Playing a variety of games, can't really have it specified towards one or the other because only 300$ to spend 

-I already have a graphics card he can use (Sapphire HD 6670).

-He doesn't need a big hard drive, he's primarily playing games and by primarily I mean the only other thing he would be doing would be middle-school school work.

If you guys need any other info just ask, I would rather you ask/it take more time to do this than just run through it all. (i reallllly don't want to screw anything up)

O.o for 300 that is a little rough personally but this is the best i can do is $340, that is the cheapest and safest system i could do with the budget your saying. Hope its ok for you!

 http://pcpartpicker.com/p/2g7qy

There is no GPU in that build.

I love budget builds, couple questions. Is $300 out the door or $300 once you factor MIR?  You need a monitor so that's $80 min.  so your looking at around $220 which is tight.   Do you want something that is you can upgrade as he gets older or something that's good for now?

$300 out the door  http://pcpartpicker.com/p/2g7V5.  Couple bucks over the budget but will get the job done. 

You said this was a gaming PC without knowing what kind of games may i suggest going slightly over budget and getting something that will deliver a little bit better performance. 

$360 out the door  http://pcpartpicker.com/p/2g8Js Differences are upgraded the CPU to the "factory overclocked" version of the one in the first build.  MOBO has USB 3.0, Case with better airflow design and Front USB 3.0 and a sold PSU that will be able to handle any future upgrades to the GPU.

 

No need for a GPU he already has one as he stated before hand.

Nice build at the $360 i went with the 740 cause it is a quad core, but the 370k was i good choice!

Thanks yeah got to make sacrifices for budget builds, went dual core so could go dual channel memory and at a fast seagate drive.

Ohh yeah i can understand hell of a build none the less with a tight budget o.o

 

I've made some changes to 300$ build (it's a couple cents away from the original based on others posts) and i was wondering which build would perform better. (i'm still trying to just min/max everything the best I can)

i am a gigantic derp, forgot to add the build
http://pcpartpicker.com/p/2hans 
wow how do i forgot the only reason i'm posting o.o

 

Here's updated one cause the promo code on that case expired.  Also if your going with a single stick of RAM i would go with 1600 over 1333 to give better performance.  

http://pcpartpicker.com/p/2hxtp

As to the question of which of the two has better performance the 370 is better choice, and it's only $10 more than the 340.  as for memory dual channel will give you slightly better performance than single stick. but going with a single stick now will make it lot easier to upgrade to 8GB in the future.