Depends on the brand of milk bag u using. I used to buy lanisoh from US, but now no friends fly there so i using Jaco ($15 for 100pc) quality wise i dun really like cos cant flatten den takes up space in the chest freezer. Downsize for chest freezer is when u store those below, u have hard time digging it out unless u label on top. Mine also using the inner white, easily get frosted, so i will have to wash it every 3mths to melt everything inside before putting back the bm. For me i tink i save 80% if i use bm instead of fm cos i dont need spent extra cost on pump, chest freezer, milkbags,(all was my old ones). Only replace my pump parts and replenish milk bags lor.
Somemore i pump for my #2 to drink 2x a day, so she also cut on her fm to 2x a day.
FM price : est $60 (400g) for 1week x 4 = $240 (jus top up abit can buy chest freezer) -1mth. (As bb grows bigger, fm is cheaper, but their intake also be more)
BM price : TiMe spent to pump (endless) + milk bag (maybe branded $0.30) x 4pack a day x 30days
Even after u stop pumping, at least can store enuff to last weeks,or even mths! I max store up to 6mths, if over i also wont use, will go and soak legs lor.. Even thou chest freezer can be up to 9-12mths.. The longer u keep, the less nutrients, and cos its OLD MILK, the nutrients baby take in is insufficient as the current age.