Everything in the game is horribly overpriced, events are geared towards someone paying hundreds of dollars in order to get most of the event rewards, some planes and carriers available only from monthly passes require you to spend $1k per pass on multiple passes. There are numerous events that only give a plane or carrier if you spend 600 dollars. Most of the carrier and plane evolutions require four purchases of 40-60 dollar packs. Keep your recipts as purchases frequently don't get delivered