I don't know what pump you use, but I use the Medela PISA and the $3 gerber bottles fit the pump so I use those instead of buying the $20 Medela bottles. Just in case you decide to replace them you can get them way cheaper. I pump into those and store in the Avent bottles that LO uses, or the storage bags for the freezer.
I use an Ameda PY. The gerber first essentials fit the pump but don't fit the base which isn't a big deal when I'm at home vs. pumping in car when H drives. If they don't come clean, maybe I'll just do that instead. Unless there is another cheap gerber bottle I don't know about.
BTW: your LO is too cute... love that hat!