not speaking from experience, just from research.....
i've read it is cheapest to just get a taxi to and from long beach or sna if there are 3 or more in your party if you can get the disneyland "flat rate". If you go on the anaheim yellow cab website and then go to the airport tab it lists the prices of flat rate services to your hotel as long as you know the hotel zip code. It is usually under $50 one way and you have to call ahead of time to get the rate. Not sure if a taxi can provide a carseat for your two year old, it might be better for you to bring your own from home and baggage check it since airlines wont charge you for this.