It costs about 10 cents per 100XP through trading card bots, and about $1 per 100XP with the event. It's pretty obvious that it's not that good. The only thing this event did was bring a pretty decent way to level up into light, so even the people who didn't care about it before would finally be leveling up more. (It also enables a way to level up extremely cheap via buying CS:GO keys during the event, then trading for card sets. In total, after selling all the emotes/CS:GO cards/redeeming the tokens from upping your capacity via buying CS:GO keys, you can get each 100XP for 0-4 cents per set for a while before it becomes hard to find cheap sets.)