Welcome to the site !!
I guess it depends on what your needs are , generally the "cheap" kits are basically what you pay for them to some extent ...usually the chain is not high quality and will stretch easily or sooner than more expensive brands ..... not saying they won't work for certain purposes , but definitely not for all use , simple street or light riding where there is no strain on the chain , they do fine , but use the chain on a trail or race bike where demands are higher and they simply won't last .....
Higher quality O-ring and non O-ring chains are usually made of higher tensile material which means they are less prone to stretch (it is not so much that the links themselves physically stretch , but the rollers and pins tend to collapse and wear) .....
As far as sprockets go , again same thing applies as far as use goes , a Aluminum sprocket (they do not make Aluminum front sprockets) are usually made for racing , mainly for the light weight , they are not made for longevity , Steel or Titanium sprockets are designed for strength (Titanium is also a very light material so you get the best of both worlds , except at a usually much higher purchase price) , steel will usually outlast a Aluminum sprocket 3 to 1 or more .....
The best option for most is to buy steel sprockets for longevity and a decent chain for longevity .... at a mid price compared to buying Aluminum sprocket and expensive chain kits
That said , I have bought $50 chains and got the better part of a season out of them riding MX with a 450 ..... but not as long life I get out of a $80 or more chain ..... , there is always a compromise between savings and strength and longevity
I know that may not have given you a direct answer , but there are so many variables , that it is almost impossible to say , "buy this it will outlast all others and do so at a bargain price" , just too many factors ..... you basically need to decide what you are willing to compromise and what your specific use and needs are ... budget is also a major factor , you can spend upwards of $150 on a chain/sprocket set , and depending on the use , you might not be any better off than you would be with the $75 or $100 set ....
Hope that helped ....some