Quoting Dani Bryant-Murray:" Is it necessary to have a breast pump if you plan of breast feeding? I am totally fine with the idea ... [snip!] ... without it. So yea, I guess my question really is : Is it a necessity to have a breast pump if you plan on breastfeeding?"
No it is not necessary but it is handy for when you will want to have a few hours off. A hand pump that you can buy at a drug store is fine.
FYI - "supplementing" with formula is the number one way to sabotoage breastfeeding! It is a major booby trap. Your breastmilk supply is determined by the baby's demand so if you give formula you send a message to your boobs that baby is eating less and you start to produce less milk.
Offering a bottle of pumped breastmilk occasionally if you need some time off is okay AFTER 6 weeks of age. It is important that newborns are not exposed to any artificial nipples in the first 6 weeks (that includes bottles and pacifyers/suckers) to avoid nipple confusion and ensure that they learn how to BF well and your supply is able to come in to fully support thier needs.
BF is really easy if you get good information but watch out for Booby Traps!