It hasn't been more than a week since Happy Pets first introduced pigs for adoption, and now they've followed up with four new colors: Black, Hot Pink, Blue ("Blueberry Oink!"), and White. As you can see in the image above, these are Facebook Credit only, and each color has a different adoption fee.
The White piglet costs 24 FB Credits, just like the Blue one. Hot Pink and Black are the most expensive at 36 Credits.
If you're desperate for one, but can't cough up real money, try buying a Mystery Box using your coins. While it's incredibly rare, we've discovered that it's possible to get a pet that normally costs FB Credits to buy.