I tried collecting used jars of 4-8 oz (even buying some), and it worked, but I find I had way too little or far too much for 1 jar.

Those bins would be nice, but I started using these little plastic bins. They are more $ per, but are more space efficient. You gata be careful of the size through, the first ones I ordered were tiny.

Or if you have tiny amounts of a lot of different small rings, harbor freight sells a set of tiny little storage boxes for cheap. They are ~1.6"x1.5"x0.75", so they don't hold a lot.

Also, one thing that worked out shockingly well was I bought a cheap set of food containers at ikea where its 17 pieces stacked together of various sizes. The lids kinda suck, but some masking tape and they hold.