I have a case, power supply, hard drives, and optical drive.
Barracuda 1.5TB, $65
Corsair CX430, $20
Samsung SH-222, $14
Rosewill FBM-02, $20
These are not needed since garcias states he already has them.
Before you buy anything, you need to understand the basics about CPU/Motherboard compatibility: Intel vs. AMD. On top of that, Intel & AMD each have 2-4 different styles (or sockets) that are available right now, and they don't always play nice with each other. For example, you can't buy a socket 2011 CPU and get it to work with a socket 1155 motherboard. It may sound daunting, but if you look at enough builds and do enough research it will start to make sense. Word of advice:
post anything you plan on buying before you actually do and let us help you figure out whether they are compatible.
Most people on these boards like Intel - and for good reason: they're reliable, fast, and Intel makes the fastest consumer CPUs. Period. Of course, these CPUs are WAY out of your price range. In the range where you're looking, AMD offers very competitive CPUs. IMO, AMD can offer some of the best bang-for-buck.
Kleinkinstein, recommended an Intel-based build. Below is an AMD based build:AMD A6-5400K Trinity 3.6GHz (3.8GHz Turbo)
$75ASRock FM2A75M-DGS FM2
$51Patriot Intel Extreme Master 8GB (2 x 4GB) DDR3 1600 (PC3 12800)
This CPU includes a graphics card that is similar in performance to the 7770 listed above. Provided the components you already own are compatible (you don't list them, so I don't know), this will get you under the $200 mark.
Also, you didn't mention an OS (like Win 7 or 8 ), so I don't know if you have one, but if you don't, that will run you about another $100.
Hope this helps.