Before I ordered that I'd want more specifics on the barrel and the bolt.
An AR-15 is like any other rifle at its core is essentially a barrel, a bolt, and a trigger/ignition system. If those parts are of good quality then the rest of the gun will most likely be acceptable as long as everything is dimensionally correct and is not otherwise garbage.
The kit in the add mentions a grade of barrel steel, being CM 4150 which is a good sign, with a 1:8" twist which is perfectly acceptable and will handle a wide range of bullets. What they don't specifically address are some crucial details.
1.) Is the barrel chrome lined, or salt bath nitrocarburized? If yes, then great it will give a very long service life and be easy to maintain. If not, then I'd pass.
2.) What is the chamber actually cut for? .223 or 5.56mm NATO? The chamber specs are not the same, the 5.56mm NATO chamber is far preferable if you want a general purpose carbine that can digest both commercial and surplus ammo. Remember 5.56mm NATO is loaded quite a bit hotter than commercial .223 Remington, and the NATO spec chamber is more forgiving of this higher pressure.
3.) What inspections has the barrel been subjected to if any? High pressure testing is standard, and desireable. Same for magnetic particle inspection. Some barrels even get multiple x-rays taken like those offered by SIONICS Weapon Systems.
Also need to know more about that bolt...
1.) Has it been HP tested and MP inspected?
2.) Is it at least Carpenter 158 steel or a better grade?
3.) Was it shot peened like a good quality bolt should be?
I would also like to know if the gas key on the bolt carrier group is already installed and properly staked. If not the end user can do this, but it is important.
The GI trigger at least is a known quantity.
Generally if I were building to a strict budget I would put my hard earned $$$ into a barrel of good quality ready for a long time of hard use, and a good quality bolt. If that meant no fancy hand guards or free float rail at first then so be it. Start with a solid core and get a reliable durable rifle first, then worry about personal preferences on furniture etc.