Who said 20-30 Euros? If you have to pay 40 euros for a PSU then buy a PSU with 40 Euros from a Good company or pay 20-30 from a bad company, but this will destroy you (cause bad psus can damage ur system)
I can't say I've hand any issues with mine being unstable. I have mine overclocked to 1044/2088/2149 and it's really stable, only a driver crash here and there.