Don't cheap out too much on some of that stuff. Cheap headsets are garbage, make sure you find something with sealed cartridge bearings. I prefer Cane Creek as I have used them for many years with no issues. Cranks are also a good place not to be so cheap, remember rotational weight is the worst weight so having something a a little lighter there will be handy. Also again the cheaper cranks can use a softer aluminum which can strip easily when installing pedals or the taper could deform and you won't have a tight fit. Also sealed cartridge bearings are great for your bottom bracket as well and if it is a square taper BB make sure they use metal cups not plastic as those can crack easily and are just not worth it when you can get a metal cupped version pretty cheap.

Everything else said is pretty reasonable though. A heavy seatpost or bars won't really effect much aside from weight. Good wheels are helpful and preferably find ones that are hand built by a professional wheel builder because they typically will last longer and not go out of true often if at all and you are quite unlikely to break a spoke (except maybe for low spoke wheels or super heavy touring). Your contact points are also important so get some good grips or bar tape (and certainly if it is a drop bar find one that is comfortable rather than just cheaper) and a decent saddle but know most manufacturers will make a similar saddle with a range and the nicer ones will have ti or carbon rails and possibly other lightweight benefits but the overall shape will be the same.