It's a good deal for the price. You could get an Antec VP-450 which would last longer, and is $36. It's of better quality than the CX-500.
You wouldn't even need 300W for your build, so the 50W difference is negligible.
Both are good power supplies, go for whichever one you like.
You won't need a TX/GS power supply, those have way more wattage than you actually need, since you don't have a graphics card. Antec, Corsair, and Seasonic are some good brands around that price range. The Seasonic ones are better, but have lower wattages at this price point.