Do you think i need to change anything or improve on. I would like to try to drop the price without losing very much power. I'm trying to stay on a budget of $600. I already have a hard drive that is 500GB
Right off the bat though I'd tell you that the GTX 640 is garbage and the same price in that link as a newer GTX 750ti. The 750ti also uses the Maxwell architecture which is more efficient and less power hungry so the card is completely supplied with power through the PCIe slot.
If you are set on that case, then here is a much better build. It has the LGA 1150 platform, so if you want to upgrade to an I3, I5, or I7 later then you can. You can overclock the G3258 and get performance similar to an I7 in gaming. And the graphics card being the R7 265 performs better than the 750 ti in most cases and is the same price as your GTX 640. I only put a single 8GB stick of memory, ECC memory is not necessary for a personal computer but rather for servers, so that if you want to upgrade later then you can pop in another 8GB stick.
Another thing would be to try and get an SSD in there, it not absolutely necessary but it will make everything a lot more snappy when navigating inside the OS.