Cheapest and best do not go together.
If your usage is not fast action gaming, then the cheapest is to use integrated graphics.
$80 is about the cheapest price you should pay for anything close to a gaming card.
The GT730 64 bit falls into the ok category... barely.
http://www.newegg.com/Product/Product.aspx?Item=N82E16814487052
Note that the 64 bit version is actually faster than the 128 bit version.; do not confuse them.