I use these
https://www.addis.co.uk/seal-tight-330ml-beaker.asp
They have a screw top lid so completely leak proof. No small parts or seals, so super easy to clean. And the round shape makes it easy to tip the powder into the shaker.
They are a little bigger than necessary - you could probably fit 6 scoops in. Personally I prefer 100g per meal.
They do the job though.
I bought a pack of 5 for a tenner.
I tend to weigh out 5 meals worth and have them ready to go.