I certainly agree that it costs a lot of money to run any business, Colette. I know that as well as anyone. However, if you're paying between 40%-50% of gross sales in taxes alone, I would suggest you have a chat with your accountant. There is no way that tax on the sale of merchandise (regardless what type of merchandise it is) should run 40%! Regarding the other expenses that you listed "Then there is the percentage that goes into running the business, things like maintaining the rodents, water, power, supplies, new cages, new morph, shavings, hired help, advertising, etc.", most of these are tax deductable as operating expenses. These are fees and costs that you incur as necessary evils in operating your business. These expenses are then listed as "deductable" against the tax you owe.
No one would ever argue that it costs the best breeders such as yourselves a ton of money to operate the way you do. Having a top-notch facility like yours is not inexpensive to own and operate. No one can (or would EVER) question the time, labor, love, blood, sweat and tears that you folks put into your operation. You are 2nd to none!! Your passion and dedication is what places SK amoung the top breeders (and individuals!) in the world. For that, I am extremly grateful and appreciative!!!
However, the topic of this thread was basically "who should pay the freight." And again, freight is a deductable expense (for the SELLER) and there is absolutely no way it could possibly approach 10% of the gross sale!! That would mean that on an average sell price of say $3,000 your freight cost would be $300?!?
I respectfully agree to disagree on that specific topic. 
Tim