TheraBands are readily available and won't have the delivery driver cursing at you for ordering weights. They are just as effective.

I just bought a kettlebell last week on Amazon and it came today. It was the last one of its model, but I'm sure you can find some others.

I've never lifted weights before but the kettlebell sounds appealing because it's supposed to be "functional strength", not overworking a single muscle like big gym machines can.

Yes, it is pretty much impossible. Buying weights off craigslist or Facebook has always been the better bet anyway, because it's not as if a chunk of iron can get worn out and they are much cheaper. Listings are probably harder to find and more expensive, though.

You can also make plates out of concrete, although that also requires more room than dumbbells and for you to already have a barbell.

Rogue can notify you when their kettlebells come in stock. I managed to nab one the other week. You have to act fast though, because they sell out pretty quick.

https://www.rogueeurope.eu/rogue-kettlebells-eu

I just bought a power cage for the garage of my new house, no problem.

Already had the weights, though.

Body resistance.