#[5]​ I would say at a minimum it would be good to have the option to say “I have X number of these items, first to people to zap me can get in on this” (inventory). As people zap, the availability changes. The zap would also include a way to share shipping info and any notes from the buyer.

Mobile friendly would be great as well.

Nice to have - some sort of reporting system where I could look back later and see sales or find orders.