I suspect that it takes a very specific amount of heat and pressure to get those tins to seal the first time, and I have never heard of anyone getting a tin to seal back using any homemade fixes. It probably wouldn't be very... let me rephrase, if someone did figure a way to reseal tins, it could lead to some nefarious practices.
As far as what I do, I am also a Mason jar nut, but I also have inherited a room full of jars from my grandparents. We grow all of our own foods, so it is an important part of our subsistence. I do not personally find it daunting to keep a closet and a cabinet full of jarred tobaccos. But, some people may have space issues in their situations. If it were me, I would invest in one of those sealers. I'm not sure if a vacuum would be beneficial for aging, but sealing a bag could definitely help with making sure air doesn't permeate the bags.
Now, when I pop a jar, if I do have a tin that would work well for the blend that I open in the jar, I will sometimes put enough for walking around with in the tin. I especially love those square tins, because they fit in my jacket pocket perfectly. Carrying a jar around is just... awkward.