I guess you're talking about the M&P-15 Sport at that price range. Lots of good reports and few bad, it seems to be one of the best entry level ARs.
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together.
US Army 1966-69, VFW Life Member, Retired Geek
I can't find a bad thing about them. And it feels like a solid gun. I hate the grip on it though. Would be my first mod.
The only bad thing is... It doesn't have forward assist and ejection door. To most people, they are barely needed. U can change the grip to the Magpul MOE.. a very inexpensive replacement. Less than $30 brand new though.
And i have one.. never used.. i'd sell it to you .