To the OP, I understand exactly the position you are in.. like many have said.. you could save for another 3 months and buy a "nicer" rifle. I purchased a MP 15 sport last month and have put about 500 rounds through it. They have all been the cheap steel cased monarch rounds that you can get $5/box at academy. I have never had a single failure to fire, failure to eject, or failure to feed. The rifle is nuts accurate and I am fully confident that when I pull the trigger that it will go boom and hit whatever I am looking at through the irons. The farthest I have shot it is at 100 yards and does it without a problem.
I got mine for $650 out the door (gun show) and haven't thought twice about it.
Disclaimer: I do need to add this section.. if you plan on doing any of the following, you might want to try another:
1. Bury it at the beach for extended periods of time.
2. Belly crawl with it through hundreds of yards of swamp and mud fields.
3. Use it for years without cleaning it.
However, if you plan to take it to the range, home defense, and hunting, and clean and lube it after each use then you will not have any problems. Don't let the more expensive name brands turn you away from the AR platform or try to intimidate you into thinking that it's a "bargain bin" rifle.
Just get it and enjoy it.. Look all over the forum, everyone that has purchased the sport has been happy with it.