This discussion came up a while ago.
Yes, unauthorised copying (even if the copy doesn't specify who/what it is) is illegal. It is also illegal to make a copy of a person's likeness without their permission (so JasonB, having Russell Crowe, just happening to be dressed as a Roman general is also illegal).
However, as some have stated, it appears that this is a drop in the ocean for the copyright owners and probably isn't seen as worth pursuing (beware however, Disney is notoriously litigation, so purveyors of faux 'Jack Sparrows' beware).
The real issue is raised by Tony Dawe: it's not a crime to buy them, but it is a matter of personal conscience. As he says:
I'm guilty of knowingly and directly supporting illegal intellectual property theft and copyright infringement by purchasing these products, and so is everyone else who does the same
Routes out include the old idea of 'stick it to The Man' hippy/student trope about 'liberating' goods from stores and the 'public good/public harm' argument that no real harm or loss is involved (well, technically the global Mega-Corp copyright owner is losing several $000s in licence fees... but they earn [milking/exploiting?] $bns anyway, so they deserve it; or do they?... discuss).
Of course one can also argue that the fig manufacturers are (probably knowingly) breaking the law and are intentionally sailing close to the wind, knowing that they'll probably get away with it. Which gets back to Jonathan's point and raises issues of whether in buying such figs (knowing that they're not licenced) , buyers would be, at best, acting immorally and, at worst, complicit and an accessory to crime (like with buying stolen goods). As far as I can see, few legislations do this although France and Italy have made buying knock-off handbags etc illegal.
All a bit of an ethical minefield, but I suspect that as Tony says, the argument that the harm (ie financial and potentially reputational loss) done to small fig manufacturers by re-casters is of a different order relative to the harm done to the Mega-Corps would prevail with most modellers.
Ethically this doesn't hold water (killing someone a bit is the same as killing someone a lot), but it no doubt serves as a rationale for many.