Examine your film developing tank(s) to check on the maximum amount of solution you will need to develop the films you intend to develop.

Then buy one or more graduates that are at least that size.

I have some 600ml plastic kitchen graduates that I paid about $1.75 each for that serve me well. Plus some 1 litre ones for which I paid even less.

And a 45ml Paterson graduate for measuring smaller quantities.