I will put out a different opinion than I have seen so far here.

You are working to get into the army.  You aren't there yet.  That means you are about to go away for basic training and AIT.  You are looking at several months of training.  Then you will go to a first duty station and be starting out there.  Have a gun at your first duty station is a bit of a pita.  

You should really look into this before you grab one up.  I don't think this is a good time for you to buy one.  Down the road most definitely but it looks like you could use some more research on what you want and what things should be worth.  

Put aside a bit of money now for one and then save a few bucks out of each paycheck with an AR in mind by the time you are done with training and at your new duty station and settled in you can buy something very nice with a military discount that you really want.  Buying this now will mean it will sit at home for month and lose more value as it has had another owner.  It isn't worth a thousand in the first place and unless we have another panic you are looking at a resale value of 500-600 down the road.  Prices are only going down for right now and there are still plenty of folks who bought very expensive low quality guns during the panic who are trying to get rid of them.

Just a heads up--CDNN has Colt 6920s for $949 at the moment with the Magpul version for $999.  Call CDNN at 1-800-588-9500 (or email me and i'll forward the emailed-flyer to you).

Here you go. Merry Christmas

I got 16 years in the Navy, but I have Army in the family.  Good call on holding off.  Get through basic and see where your orders take you.  For all you know you could be overseas, or in a state where you can't have a full fledged AR-15, like California or Hawaii.  Living on post means you'll have to keep it at the armory, but that's not a deal killer.  The big benefit is once you qual on the M4, you'll have a better feeling for what kind of rifle you want for yourself.  I have a feeling you'll be spending more time marching and doing rifle drills than shooting for a little while.  Take the time to concentrate on getting through training and getting a good MOS (in the Navy we say "Choose your rate....choose your fate", some are way better than others.  Then you can buy something you can be really proud of, like of the many top-tier AR's other posters have mentioned.  Not too many E1's have the scratch to buy a $1500 rifle, they can barely pay for their car/insurance/bar money.