Here's something to think about.
If you buy a kit from Model 1 Sales it'll cost ya' $400.00 plus shipping.
If you just order the upper w/bolt assy. it'll cost ya' $370.00 plus shipping.
That's only a $30 dollar difference.  If you need an A2 Stock Assy. it's $55 and a Lower Parts Kit is also $55 for a total of $110.00 plus shipping.  
  If you needed a new upper for your AR you'd be better off just getting the whole kit, that way you save money in the long run and have spare parts if you needed them.   Now if a complete upper only cost $290.00 it would make sence and I might own several uppers and not end up with a ton of spare parts.  
 Talk to ya'll later.  TN.Frank