What's the point of getting a mark?
As soon as they come out with the "real" mark, you know it won't take the counterfeiters any time at all to copy it and sell it for cheap on ebay.
See, I thought of that, too, but then I remembered (with a distinct shudder) my own religious training on this subject:
The only ones who won't want that mark should be lapsed Christians who know what it signifies, and what it portends for them if they do take it. (Eternal damnation.) They won't want a counterfeit version, or any version, although there might be some who would sacrifice themselves and take it anyway so they can provide for those they love. Without it, you won't be allowed to buy or sell (although, and I'm serious, I guess that means God hadn't heard of the black market when he revealed all this to John).
Anyone who does want it will be given it freely, so there won't be any need to counterfeit it. Some may, according to Hal Lindsay (
The Late, Great Planet Earth), be forced to take it, but Hal thinks God will forgive them.
The rest are intended to be martyrs for Christ. See, they could have gone to heaven in the Rapture, but they weren't right with God. So they got "Left Behind" (another book about all this end-times stuff), and now can only get to heaven if they are dedicated Christians when they die. Which will usually be by decapitation, because those who refuse the mark will be executed.
So, no; there won't be a huge counterfeit market, I wouldn't think.