Smeagol, if you KNOW that certain companies are selling recast--ILLEGALLY recast--figures, then I would urge you to NOT patronize them. You are essentially dealing with thieves.
These people are stealing from people who make their living by spending the time and effort to craft and sculpt these very figures that you love to build and own. If you buy stolen products, you are really cutting your own throat, because if you remove the profit motive from the people who make the original items,then you willbe quashing the incentive for people to make new ones. WHo wants to spend time and money to make something when they're not going to reap their rightful profit from it? If you're buying ANYTHING stolen in this surreptitious manner, you are not only breaking the law, you are hurting the very industry of the genre that you love.
How do people get away with it? Simple--criminals have a myriad of ways to disguise their activities. It IS possible that they share the profit somehow through some deal or licensing agreement, but if you're suspicious of their products, you should enquire what the legitimacy of their products is before you buy.
When we went into Russia, we simply could not believe the amount of bootlegged material that people were setting up and selling outside our shows. Cheaply made garbage, but selling it for cheap, so people were buying it. There was no way to actually stop them because "everybody" was in on the take. SO we cut a deal with some of the biggest ones--we allowed them to sell inside the doors, and then took 50% of their profit. They sold a lot, and we at least got paid for their thieving of us. Not a perfect arrangement, but better than nothing.
It's possible that these sites have some sort of arrangement of this type with the original sculptors, but not likely. The best thing you can do is to not patronize this type of illegal immoral behavior, and know that you are legitimately supporting the people who produce these models out of the same love with which you build them.