I see this often enough that I feel like I need to address it.
The value of a collectible coin doesn't have anything to do with its face value.
"2x face value", etc, is simply not how coins are priced, and it doesn't make sense to say things like this.
Here's how a coin is priced:
For bullion coins, like Krugerrands or silver Maple Leafs, the intrinsic value is the value of the metal. For a Casascius coin, the intrinsic value is the face value plus the value of any precious metals.
The numismatic value is the amount of additional money the coin would fetch, based on its rarity or desirability as a collectible.
The seller's premium is the profit margin of the seller.
Note how there are no multiplication (x) symbols in the above equation; only plus (+) symbols.
Using the "?x face value" system does nothing but help people with high-face value coins rip off the general coin-buying public. "Buy my 10btc coin for 30btc -- only 3x face value! It's just like getting an 0.5btc coin for 1.5btc!" -- this glosses over the fact that the seller is asking a TWENTY BTC PREMIUM for a coin that's not even one of the most rare Casascius coins. Think about that. Even at today's exchange rates, that's a TWELVE THOUSAND DOLLAR premium. For a privately-minted round issued in 2013.
Go into a coin store and tell them about this, watch their jaw hit the floor.
Something to think about