No power & no diagnostic leds ...?

Hi, everyone I need some help with with my Imac. The thing is that a couple of months ago it started to fail and I had to disconnect before power it on at the point that one day stop working. I already check the diagnostics leds and there is no leds on... What you guys think ? Power supply ? Any recommendations where I can buy it, I'm looking for a cheap solution so I don't mind if is refurbished ...

Thanks;

Elliot