Zulily has the Green Sprouts Containers for sale again. Last time they sold these, they sold out fairly fast.
They have the 10-piece plastic set for $7.99
Or the 5-piece glass set for $6.99.
Just search “green sprouts” and you’ll find them.
These are designed for helping store baby food but I use them for all sorts of things like making little cubes of broth or freezing herbs or storing some leftover blended fruit for smoothies. They are really nice as they stack right on top of each other if you buy more sets. They also come with little labels so you’ll know what you are storing!