Yeah you would have to check the system to make sure it works fine so thats a risk. You would have no warranty on anything. I would just do some research and look at tigerdirect and newegg everyday if you can get all the stuff you want through their deals might take longer that way but you could save some money.
Just get a larger ssd rather than raid 0 two. Its not really gonna give you a performance benefit to raid those. I would just get one larger hdd as well for extra storage.