There's not currently any way.
They might reappear on a later event but as we're not a full year into cycling through events with Golden levels it's hard to predict what will happen to them ongoing.
As they've made them something you need to buy these days rather than simply win not sure if they'll incorporate them another way into events or not, players that have paid for them this time around could have potentially just got charged for something they could have waited for and got them for free.