S.L.
Another option is measuring your basal body temp each morning when you wake up. You can read more about it here http://en.wikipedia.org/wiki/Basal_body_temperature. You have to buy a special thermometer for that specific purpose (but I think mine was under $10 at Target) and remember to take your temp each morning before you get out of bed. I had a paper chart next to my bed to write it down, but I also used a website (there are many, but I used fertilityfriend.com) to track it and the site will keep track of when you ovulate. It's much cheaper than the ovulation kits.