Personally I planning bf but if I end up on formula for whatever reason I will give stage 2 and 3 or follow on maybe is called in uk until 1 year old and then special cow milk for toddlers from the supermarket . ( the same as the adult ones but with enhanced calcium, iron etc etc) by that time the baby will be on solids anyway and the cost will not be so terrible as it will be in less bottles (cups) per day.
I also plan to follow the Greek whining scheme rather than the Norwegian one and introduce first protein and lipids and vegetables and much later other carbohydrates like porridge and cereal, bread etc anything will gluten really.
But for now those are only thoughts, GOd knows what I will do with a hungry screaming baby lol...