Containerized figs.....
Yes, they can be very heavy. Use dollies to move pots around.
Bigger and bigger pots....That depends. If you want decorator-type pots, yes, they are expensive. Containers could be either pots, or, storage tubs from Home Depot. Rubbermaid makes different size storage tubs. I buy 18 gallon tubs, drill holes along the bottom-sides, fill it with a soiless, quick-draining medium and plant my 6 ft. trees. When you root prune, replant the tree back into the same container filled with fresh medium. That tree can stay in that same container for years to come without potting up into bigger containers/pots.. Prune back the top to keep the tree manageable. You will get all the figs you need from a 5ft - 7ft tall tree with a nice rack of fruiting branches. I get dozens (60-70, or, more) of perfectly ripe figs from my single-stem trees each year, and ... with very little splitting and souring because I can control the water reaching the roots....something that you cannot do with in-ground trees.
The truth of the matter is this: You can control the growth of the tree. If the trees "grow like weeds"...pinch back the growth to 6 leaves, or, if you must, prune back the branches. If you do this, you will not constantly search for larger pots. Of course this all depends on the ultimate size of the tree/bush that you want. A 6ft - 8ft tree is all I need. All I have to do is just reach up and pick...no ladders. Fruiting branches are trained at eye level, or slightly above. Very convenient. When you pinch back, and prune, you will also induce back buds to break, and the tree will grow more fruiting branches. More figs for you.
Hope this helps.
Frank
PS. Containerized growing methods for figs require attention, especially to watering, and nutrition. Granted, it is not as forgiving to inattention as in-ground growing, and you must provide everything the trees will need. I don't mind at all...but, it's not for everybody. The trees become "pets"...and, need the same attention.
Pick your poison