The obvious solution, then, is to just buy your Defenders in bulk. Ex Army UK somehow acquired 43 Defender 110 Puma models from military surplus. And get this - they're new. Yes, the diesel-powered beasts of burden were bought by some government agency and put in storage. They were bought between 2008 and 2009 and look pretty much pristine. The downside, at least for our friends in the UK, where the Landies are located, is that the vehicles can't be operated within the UK or European Union. We promise, if they're sent to the US, we'll take very good care of them.
We won't even attempt to hazard a guess at how much it'll cost to acquire this small army of SUVs, but it probably won't be cheap. Still, if you're contemplating starting your very own militia, 43 rough-and-tumble (and new) military vehicles would be a solid start.