I wish there were a few more instruments readily available to sellers and buyers.
One would be a way for hobbyists to more effectively market and track their inventory to facilitate trading and 1.1 sales. I see a lot of this done through Facebook and Craigslist when those cause topics to get pushed down and lost. It would be great to have a well-adopted trading board centered around a personal inventory manager, the same as any trading card or wine or comic book collector has.
I wish online shopping platforms which small sellers use like Square and Shopify made it simple to set up randomized draws to select committed buyers. Some people will always go home empty-handed, but that would give people without web alerts and extensions a chance to purchase the rarities. I don't love auctions unless they are for non-profits. I think mystery sales are more frustrating and customer-limiting than effective. Subscriber and early access sales just cause me to receive 150 different email subscriptions. 🙂