I upvoted you, but do keep in mind that there is a lot of loneliness and some of those animals probably save us from lots of healthcare expenses. Not everything can be brought down to simple economics.

That said I have said no to dogs myself - mostly because of cost and the constant need to be looled after - and the animal we do have is a rodent that we got second hand, meaning that food cost is leftover carrot shavings etc + a bit of hay