The annual cost of food for a guinea pig runs at least $175, as of April 2015; the cost can be higher for guinea pigs that eat more. Pellet bags cost about $15, and guinea pigs consume two to three a year. They also eat hay, about $12 a month.
Guinea pigs also eat vegetables and fruit, but owners can share their own with their guinea pigs. Safe foods include carrot peels, celery leaves and strawberry hulls. The cost of a guinea pig's vegetables and fruit can be nonexistent or as high as $20 a month. Guinea pigs should also get vitamin C in their water, and the vitamin C costs about $16 a year.