I'd have to say, it's much easier to just include your "costs" into the end price to the consumer.
You have to admit though, even if you spent $15 dollars per snake shipped, (and this amount would stay the same for a pair as they would share the same box..right?) you are still making out like a bandit. I mean, how much money did it cost you for your male snake to impregnate your female? Probably not much, since you would have to care for them either way, weather you breed them or not. But for arguement sake, lets say it costs you $500 dollars from start to finish (give or take a few dollars). If you get 20 babies, that is 10 pairs. At $500 a pair, you have made back your money after the first pair is sold. The rest is all gravvvvy!!
So if it costs you lets say $20 dollars (and this is being generous) per pair shipped (not including shipping charges, the customer pays that) that is $200 total for supplies. The next pair is sold giving a profit of $300. Now the other 8 pairs ($3500) is all yours. I'd say it's well worth the "cost of doing business".