I use a combination of Genuine E3D and Non-genuine (Ghina) E3D parts to make up a good hot end.
The most important parts for a hot end is the Heat Brake, the Nozzle and New Thermistor. If I want a good setup I buy these genuine from E3D.
If you want to save some money just buy a E3D Heatbrake and Thermistor and the Silicone boots.
From Ebay buy the finned body and Heater block that takes the new Thermistor and silicone boots.
The advantages of the New Thermistor is they are well made and I havn't broken the wires on one since I swapped to them. the clamping type is a pain and the screw in ones from ebay, look good but are a fail also.
The Silicone boots are great make it so much nicer to use when changing colours and so little mess. Plus it makes the hotend work better.
Nozzles I prefer E3D but they are very expensive and like the Heatbrake they are just better made. For the same reason as the heat break.. the machining inside where the filament has to slide is very important to making a good reliable setup. The clone parts are not machined very well inside and if you buy a non genuine one as I some times do you have to re drill the heatbreak on most as they are undersized.
Hint: if you check the E3D site you will find links to the wiki and the drawings which tell you what the dimensions are ment to be.
Buy Buying just the bare minimum from E3D and the rest from ebay I make up 3 hotends for about the cost of one full genuine E3D hotend.