Honestly, at the price of ssd's I feel they are still optional 339.99 for a 1 tb ssd is not practical in my opinion. I mean if you want to get one more power to you but, meh. I only have two because I grabbed them as refurbished drives so, only reason I have mine. Just a personal opinion though most people will tell you to get a small one as a boot drive for your operating system so it boots faster but, if you are just getting into this I say just keep it simple and stick with the 1 tb mechanical drive for your needs. There are 480 GB ssds for 159.99 but, that's still 111 dollars more than a mechanical drive but, if you are interested in it here you go. http://www.newegg.com/Product/Product.aspx?Item=N82E16820226673
You can do a lot better within your budget but I also assume you will be gaming with this rig. If you aren't dead set on the define r5 go with something like the first link you will get great performance. If you aren't then grab the build in link number two, It will allow for the same performance at a quieter operation. If you pick up the build two mount the case fan in the front for a positive air pressure, if you have any questions and or concerns feel free to ask.