Stopped by the store today and got some jars, including some 4 oz 'ers since I have some tobacco on the way. These things are so small! I still have not used them, but I had a pound of Red Cake and a pound of Larry's Blend arrive today, and since I plan on storing those for a while, I put them in 8 oz jars. I had about 14.5 oz of each after sifting out the fines, and was able to get 14.5 oz across three 16oz jars, pretty well compressed with just enough room for the whole compressed slug to barely slap against the lid if you "pack" bottom the jar after the lid is on. You can check my math, but that's ~ .3oz of tobacco per 1 oz of volume, juust a little under 1.5oz weight per 4oz of volume, so ok that's a smaller tin of ribbon or blended ribbon within 4 oz of volume, with a little packing room to spare probably. I also had 2oz of blending latakia show up, and that filled an 8oz jar to overflowing, and I had to press it down a little more than I wanted to, and I don't even think smashing it down would get all of that into a 4 oz 'er. So I guess it really depends a little bit on what type of tobacco you have, and how firmly you are willing to pack in in there, as to whether or not a tin will fit in the 4 oz 'er. I think that this 4oz size is going to be pretty versatile though.
One thing that I have noticed with canning jars, lids and bands in general, is that you want to watch the prices when you buy. You should always be able to get these things cheaply, but some places will charge twice as much as the next guy for the glass or the accessories at least. I usually go to the local smaller hardware store and do ok there.