You want to try to get a RX 460 or GTX 1050 on sale for $100 (they ave around 110-120) assuming your in the us there is one on sale at Amazon.
https://www.amazon.com/PowerColor-460-PCI-Express-AXRX-2GBD5-DH/dp/B01J9FFV14
There is even 20 dollar rebate making if 79.99
http://venturebeat.com/2016/08/09/amd-radeon-rx-460-review-punches-above-its-weight/
it should run CS go at ulta 1060p at 140 fps.
You may be able to get away with a GT 730 as long as it has GDDR5 ram but it will run you around $70 and the extra $30 for the RX 460 is so much better depending on the rest of your PC you will be able to play newer games at 1080p even if at lower resolutions.