Stickers: The thing no one wanted and the thing no one needed.

They major issues with stickers and some proposed solutions:

They are far to costly.
You can get nitro for 9$ per month and gain access to well over a 100 different emojis, this pricing is infinitely better. Especially when you have full control over what they look like and what they have.

High lack of customizability.
You have, no control over the sticker packs that are there. It's there and if you want em you can buy em. But with emojis, you want em? Make em. Especially with how ugly the stickers we currently have are.

You can't get stickers unless you have the money for them.
With nitro, you can get your rich friends to buy em for you. However with these sticker packs, you're stuck in a ditch, unable to get any. This is like shooting yourself in the foot, getting people to directly spend less as they can't help out their friends.

The proposal:
The ability to create your own sticker packs and being able to gift sticker packs.
For a fee, slightly raised above normal sticker backs, say 9$ you'll be able to create your own sticker pack via gifs/images you have. With this you can spend money too prank your friends with an elaborate rickroll, or have all the anime stickers you can dream off.  

More money, more happy consumers, more fun.