Does your Walmart also have Colt? That would be an excellent choice.
If Colt's above your price range how do you feel about buying online? PSA is much better than Windham or Bushamster. But right now good rifles and components often are out of stock.
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