I was given a G5 17" all in one today, which is faulty, sometimes it would boot and sometimes it would just go to a grey screen and stay there.  I Googled what to do(as I am normally a Windows or Linux person) if the screen goes grey, but none of the options worked.  And doing a Option Power Up resulted in a refresh arrow and a right arrow and a watch like symbol that would occasionally freeze.

So after trying everything, I opened it up to find about 12 capacitors with bulging tops.  I am guessing these are the cause of my problems. Anyway, can replacement capacitors be bought by wandering into somewhere like Jaycar and buying them off the shelf or are they more specialized and have to be obtained from overseas?