M&P 15 keep it simple .
Here is a guy in New York that was going through the same issues as you .I don't even remember what he bought , I think the M$P 15 not sure .http://thefiringline.com/forums/showthread.php?t=500261
. You may find this helpful . The thread covers many topics so it may be some tuff reading
Really cus your on the low end of a budget It should be easier for you . stick with the main brands in your price range and you will be fine .