I think the breakfast from Kilimanjaro Coffee on Nicolson Street in Edinburgh is my favourite around here. Perhaps the only thing it's missing is a hash brown as well as the potato scone, but you can hardly complain about not having enough food. Some might remark on the absence of black pudding, but I think haggis is a better alternative. Marmalade for the thick cut toast is a very nice touch as well.
This was £9.45 in total, but well worth it for the quality ingredients, I think.