Storing expressed breast milk

[puddleduck16]

I'm regularly expressing to give baby top ups for weight issues. So what I express one day I'm giving the following day. So at present I'm using a storage bag every day.
Is there a cheaper way to store the milk in the fridge? I was thinking of a bottle but surely air can get in through the teat?

You can store in a bottle using a plastic lid so no air gets in. Depending on what bottles you have you should be able to buy a set of lids for not too much. You can buy extra lids for the Tommee tippee bottles, not sure about other brands but I imagine it's the same

I have avent bottles. I have what I would imagine be lids that would clip onto the part with the teat. That would be great to be able to use them!!