What is the best high quality and cheap PSU?
Depends on the system you are building and your budget. A higher efficiency will cost more but save you money overtime as the efficiency will allow you to lose less of the power coming out of your wall socket.
Popular choices are the Corsair CXM 450/550W, the BitFenix Whisper M and the EVGA Supernova G3 550W/650W in the lower end of things.
To add to Chill's reply, you can check professional reviews such as from JohnnyGuru.
There are a few other good ones, such as the EVGA Supernova G2 and various Seasonics. It really does depend on your budget and system.