I think, only way is to peg new card prices to USD or whatever currency.
Not bitcoin for sure, since x10 in price might make cards to expensive for anyone to buy.
Not BitCrystals since x10 of Bitcrystal price will or make cards to expensive for anyone to buy or scam those that are buying cards right now.

For sure leave already issued cards price in BitCrystals as it is now. There are only 21 issued and even if 1500 BitCrystas will be worth a fortune I think they will  eventually be sold. If to expensive and not sold, that mean that less then 1000 will actually be in circulation and that will justify higher price then the rest.