Besides buying a bag of fertilizer at the store, what can I use to make my lawn look like I got it serviced?

Is there a "magic" potion I can make at home and spray/apply to my lawn to make it green, thick, and kill ALL weeds and bugs? I have St. Augustine, bugs probably chinch and grubs, and broad leaf as well as other hard to kill weeds. I don't want to hire Tru Green again because of the cost involved.