That is extremely false information that you have been introduced to I'm sad to say. If you go to americanrodent.com you will find out that oftentimes, shipping is free. The more you buy, and the more likely it becomes that shipping becomes free as well. If you don't get free shipping, it is most likely 50 dollars or less for the shipping cost. So look at it this way.
Spend $100 on rodents and get free shipping.
Spend $50 on rodents and pay $50 for shipping.
It's going to be the same cost, it just depends on how much you really need.