Air conditioning no longer cold.

Hey all!

The air con in my 2007 Diahatsu Sirion has been out for a couple of years now. It still blows but does not cool the air (heater still works fine). I figure there is probably a leak somewhere which will need fixing before refilling the refridgerant. My questions are is this something i can easily fix myself or should i go to my mechanic, and in either scenario what are the likely costs? I'm hoping i wont have to sell a kidney just to be comfortable while driving this summer