Hi Princess,
Most of the KittyCatS cats are no copy so when setting a kittycat or a kittycat box for sale you simple right click/edit, click the For Sale box in the General tab then type in what price you'd like to sell for, then choose Original in the drop down menu right above the price box and finally select Apply. When someone purchases your kitty they will have to pick up the cat or box after buying it and then they will be all set!
Welcome to KittycatS! I hope you have fun with your kitties!