Users will be able to purchase emotes in an "Emote Shop". Streamers can choose how much to charge for each of their emotes. The user can purchase emotes from various streamers and will be charged monthly for a one lump sum per month, 3 months, 6 months, or unlimited time price. This will encourage revenue for streamers from people that don't want to pay the full subscription price. This will also make people want to collect emotes from different streamers. Perhaps a trophy system of some sort could be included with this system to encourage people to buy more emotes as well.
a one-time purchase would be great. Imagine if we can have limited-time seasonal emote packs that our viewers can buy and it's for them to keep the emote packs forever. I'd say let Twitch decides the pricing based on how many emotes you get per pack.