The three foods that are the highest in creatine are beef, salmon and tuna.
One pound of beef will contain around 5g of creatine. One pound of salmon will contain roughly 4.5g of creatine. Each can of tuna will contain about 1.5g of creatine.
Theoretically, if you base your diet heavily around those foods and are able to get about 5-10g of creatine through food alone, you wouldn't need a creatinesupplement.
That being said, a creatine supplement is pretty inexpensive and it's kind of like an insurance policy to ensure you are getting enough creatine each day. I would still use a creatine supplement like ancient strength from n2bm.com and supplement with 5g (1 serving) per day. A 30 day supply is less then $15 dollars.