This is shopping TV, what do you expect? If they sell a frying pan for 19.99 its also $10 overpriced. Its just the same with gold coins.
We have similar shopping channels here, where they tell the people that investing in gold is a great way to hedge ahainst inflation, crisis times ect. - which is basically true. But then they try to sell some gold medals (not currency coins, but private mint made with weird weights and .900 gold, to make it harder to work out the value) to the people for double the usual bullion dealer shop price.
But it's not illegal - they don't say anything that isn't true. They just hope to find some people who are dumb enough to buy from them. And it seems to work, appearantly.