The only option - don't buy. The fact that someone who sells a particularly desirable object for a higher price is nothing new; this is how the market economy has worked for hundreds, even thousands of years. However, the game of supply and demand only works - if the latter exists. The seller did not do anything illegal, he/she was simply luckier to get a ticket. Neither the police nor Digitec will probably want to/be able to do anything about it.
But it's not the end of the world for me personally, my new gaming setup can wait, let the 20 chosen ones sell their cards, eat them or even use them for gaming, I don't begrudge them! :-)