I know what you're saying but BF babies usually don't ever take more than 5oz of bm at a time. Of course some do, but not most.
For your situation I would suggest you only buy 1 small bottle before baby is born. Some babies are picky about the type of bottle too. My DD only likes wide nipple type bottles (like Tommee Tippee) where my DS would take just about any bottle.
Unless you live in the boonies you will be able to get them as needed once your baby is here and you know a bottle will work.