I apologize for not replying sooner. Just saw your question now.
You basically are getting what you pay for. My motto in life for any kind of expensive purchase has been: "Buy once, cry once." in this case, my recommendation is to pay the extra money now for a better quality built rifle, especially if you are planning to use it for self defense, training and/or investment purposes.
If you are planning on simply taking it to the range once a month and shooting a couple of magazines through it at a time, perhaps you won't mind not having a mil-spec rifle.
Here is an excellent reference site known as "the chart", which gives a very good explanation of the different parts that make up an AR-15 and which companies adhere to the US military's specs and which companys either don't adhere or refuse to respond to repeated inquiries regarding their builds (DPMS and Bushmaster, for example.)
https://spreadsheets.google.com/spr...dUVoakZ3UHJnVEE&single=true&gid=5&output=html
I'm not saying that DPMS (or Bushmaster) make bad rifles. I'm simply saying that they possibly do not follow certain manufacturing / inspection guidelines.
My personal recommendation remains a Colt. As a matter of fact, I'll shortly be ordering a 6720 very soon. I can also recommend "Bravo Company" (BCM), "Daniel Defense" (DD) and a handful of others.
Educate yourself as much as possible on the AR platform. Not just in regards to manufacturers but in proper training with the weapon. Try to make the best informed purchase that you can so that you'll have no regrets later on.