I have family/friends that treat refillable lighters as disposable. At most, they'll fill them with butane gas once or twice, till the flint runs out. I asked them to save them for me. Got a couple full bags a few months later. I also pick up the ones I find on the street, partly because I hate litter.

You can buy flints by the hundreds or thousands cheaply online.

For the cost of one lighter, you can have a hundred flints or more.

Buy flints. Buy butane gas bottles.

It is also possible to make/buy an adapter to refill lighter using larger and cheaper butane gas containers, such as those used for camping, gas stoves.

Oh, and tobacco is very easy to grow (it's a fucking weed), and once you have one plant, you'll never lack for seeds.

You can use an empty paint bucket for a plant pot and any old dirt and it will grow beautifully.