I'm glad your excited about being a Dad. I've been one for 7 months now. They are A LOT of work and expensive especially with paying a mortgage and just paying monthly bills. Then on top of that there is all the baby stuff which actually starts to get more expensive as the kid gets older.
Do things to try and keep the prices down like buy baby clothes at a salvation army or thrift store. That way the clothes are only a few bucks as apposed to the much larger price to buy them new. Epically when the kid outgrows them in a few months.
Also when your feeding the kid use breast milk over formula. It's cheaper and better for the kid. Also when you first have the baby they usually need to be feed ever 2 to 3 hours.
Also take prenatle classes you will learn a lot. yes it varies a bit from kid to kid but it helps.
Anyway good luck. I couldn't imagine fathering a kid at age 19 (if your profile age is correct). I still wonder about how I'm doing it now.