MSI Radeon HD 7850 Twin Frozr Graphics Card for $89
Though it is not the latest and the best of it's kind, this MSI Radeon HD 7850 Twin Frozr is still proven to be stable and working good, so it might be the best choice if you're running low on budget. It has a 2GB memory capacity, which should be pretty expensive for a graphics card. It is designed with a Propeller Blade that can generate 20% more airflow to cool it down. It also supports Afterburner overclocking utility so you can depend on it even if you're using it for a very long time. It also has a 10 years lifetime, so you're investments on it will be all worthy over time.