Hello! I'm completely new here and I'm already expecting to be sticking around for quite a while, so I was wondering if it's better to sell event items during or after the event? Based on other sites I've been on, the price usually goes up once an item is no longer available... but I haven't seen anyone mentioning it anywhere so I wanted to ask (plus the current sell price for some items is very tempting)! If this isn't the right place to ask / an appropriate question for this board please feel free to remove or lock it!
I think what tends to happen around here is that items may go for a lot right at the beginning, if there are any particular items that people want and don't want to wait to get. But as the event goes on and people get more and more copies of the items, the prices tend to go down.
Books tend to retain value because they are used to increase pet intel, which is is useful for people who have battle pets and want multiple copies to read to all of their pets. Items that have more than one use (food & wearable, for example) also sometimes tend to stay kind of expensive.
Also, I believe is planning on adding more achievements later in the event that will use some of the new items in them, so you may want to wait until those come out and see if you have any of the items that are required for the achievements, because the prices of those will probably go/stay up as people try to get anything that they still need for them.