So you want to have a pet. Yes, pets ARE irresistible, but hold on one minute before you even think of bringing one home. If you think that you won't necessarily need all of the above, you're right.
Costs vary, but be prepared for most of it.
Make sure you have the time, the money, and the space for the pet of your choice. Owning a pet is a big commitment, for up to 20 years, and they are utterly dependent on you during this time.