Spare Card Timing

As time goes on, the going rate for spare cards keeps increasing. On Valk, I keep seeing someone with a chat up to buy one for 140 mil. I bought mine for I think 4 mil just after the event for it ended. I've made somewhere between 25 and 30 mil from it, as I don't wear it all the time, and I don't play super-often. So I know selling it will be my best option, but I'm wondering how long I should hold out. Of course, the price will keep going up until there's another opportunity to obtain new ones. But I have a guy feeling it won't be too much longer for that.