You could halve that RAM at no real cost to performance. Though get 1600Mhz sticks.
If you want to save money in the long run, buy high-capacity HDD's now. While it is true that HDD prices are pretty high, the wont be moving for a while. Buying 3TB for $150 is cheaper than buying a 2TB now for $120 then having to add another TB for $80 later.