Having some sort of Pay shop would be great to have as long as it didn't turn things into a pay to win situation.

Having things like the ability to unlock a 2nd character on your account would be something people could pay for, without it effecting game balance.

Having something like another 4 character resets buyable would also be something people could pay for, without it effecting game balance.

Might want to think about other things like player locked cosmetic items, like a suit that goes overtop of your armor with no effects aside of visual (could have a elf suit or a santa suit for example), or a weapon skin that goes onto of the same weapon class that has no effect on the stats (like making a axe look like the xmas one for example)

Adding a optional monthly subscription that gives you some non-game braking benefits such as increased green bar gain or double skill point gain, or crafting duration reduction all seem like things that someone might pay for if it was put into a subscription, while also not braking the game for other people without it.

I'm sure theres other things that can be thought of but I really feel as if making this a large one time payment is preventing alot of new players from joining, so this may be a way to lower the game price while still gaining extra funds.