Well it is a bit fuzzy in some respects. Copyright only works IF YOU DEFEND IT. It's not illegal UNTIL you are challenged. So as long as you put the cash aside from each sale to pay the copyright when (and if) you get challenged your OK. Oh allright, I admit that is a totally immoral approach, sadly it's an approached that has been used many times in the past to great effect, often by big companies.
The trick when you get challenged of course is to say "I never intended to rob anyone, have your copyright fee." ....and then pay up.
It's not the same everywhere of course, America has far stricter laws than in the UK. I will give you an example. Bung, a Chinese manufacturer made the V64 Doctor back up unit for the N64 (
http://www.youtube.com/watch?v=jIcsqA8Dco0 ). This device was illegal to sell in the US. The ruling was that video game carts could not be backed-up as they counted as hardware, the data on them was proprietary code (protected) that made the hardware do what it did. In the UK, the courts considered the carts to be software and backing up your software to protect your investment was (and is still) completely legal. These days of course you don't get to own anything as you only have the software under license, but that's another story again.
At the end of the day of course I'm with fitzsteve on this, it is a pricy way to buy a CF card.