I think they raise the prices of cards and refresh button because some players are whining about how fast they complete all the quests. But yes, for beginners, such prices are quite unaffordable.
The funny thing is that we still get 100 coins for defeating the PM-monster, and 25 (!!!) and 50 (!) from ordinary and rare chests. Even a legendary chest gives something like 300 coins, but how often does it fall out?
Definitely need an increase in all these awards. And for an event store, it would be nice to add a third or even a fourth row with cards + toys + items/potions. For example, two rows with cards, third with mixed toys/items/potions. Okay, I got bad cards, the event ends, but there are not enough coins to refresh cards, where should I put the rest? OK, I'll spend it on Viagra or Libido or Voodoo Doll or Wasted Time or Bronze Key etc. Why not?