Flea Extermination Average Costs. 1  DIY flea remedies are widely available from shops and online retailers. Flea insecticide costs $15 to $50; a package of 2-3 flea foggers costs $10 to $25; flea yard spray costs $10 to $30. A comprehensive (indoor and outdoor) flea treatment by an exterminator/pest control company might cost $75 to $100 for an initial service or $150 to $250 for both an initial and follow up treatment.