upgrade plain pc graphics

[Mousepotato01]

I have a HP Pavilion p6-2117c Desktop PC. With AMD Radeon HD 6530D,
AMD A6-3650 APU with, Radeon HD Graphics 2.60 GHz, 8.00 GB DDR3 RAM 4GB x 2, 64 bit OS.
I would like to install a graphics card to get the most out of on line games. I play World of Warcraft, I would like to play Star Citizen, along with many other MMORPG games.
But the graphics look so nasty with stock items I seen what games look like with a few upgrades to a plain computer, this is why I want to upgrade my system.
I want the best picture and FPS for the smallest cost. I have a very limited budget to work with also $50.00 would be great but I know better lol but please keep this in mind.
Please let me know what would be the best card to buy. If there is any other hardware you feel must be upgraded along with the new card please give me type of hardware to buy.
My computer has not been tampered with aka upgraded in any way with improvements. It is still the same as the day it was packaged for resale.
Thank you in advance to this awesome community. I have been told many many times to come here specifically for any advice I might need.

 

[Rhezner]

http://www.newegg.com/Product/Product.aspx?Item=N82E16814127788&nm_mc=KNC-GoogleAdwords-PC&cm_mmc=KNC-GoogleAdwords-PC-_-pla-_-Desktop+Graphics+Cards-_-N82E16814127788&gclid=Cj0KEQjwiN6sBRDK2vOO_vaRs5cBEiQAfsnJCUiNydMo2JB3gyPIiY96es8tlylbZPwZKcPpGif4epQaAjHw8P8HAQ&gclsrc=aw.ds

here is a gtx 750 for 65$, you should also look on craigslist and ebay for a cheap 750ti or an r9 270.