For our purposes, MILSPEC or surplus gear even if unissued is in most respects inferiour to decent quality climbing and outdoor gear. There are exceptions to that statement, like the Cammenga compasses, Doan's magnesium block and some other bit's and bob's.
If your trying to buy cheap, for whatever reason, then fine. Just be aware that the weight penalty adds up very quickly.
I'm not a great fan of 550 cord. I prefer to use the cords sold by reputable climbing outlets.
That is for two reasons: 1) You have a choice of sizes and strenths and 2) Its designed not to kink if it gets tangled. A major consideration if the conditions are, shall we say, less than optimal. (oops, Brit understatment again...... Sorry guys. <img src="/images/graemlins/smirk.gif" alt="" />)