£11 for a 500W power supply, I can 99.9% guarantee, will be utterly shite and unreliable!

For the last few years, I've always sworn by Enermax PSUs......a few examples in the link below:

Enermax Power Supplies

Oh, and no, newer power supplies will normally come with more than enough cabling & connectors pre-connected......you don't need to mess around with opening them up (highly unrecommended) to do anything.