Don't buy live! They are sometimes twice as expensive as frozen. What you can do is bulk order online. Now, shipping is usually $40-$50, so in order to get the most bang for your buck, you'll need to order a lot in bulk and just store them in the freezer until you need them (That's what I do). The other option is trying to find a rat breeder in your area that charges less or see if there's a large frozen rodent supplier near your area.