You might need to partner with one or more authentication services.
I think this is an interesting idea but convincing people to participate and building up inventory is going to be hard. Besides, what if people agree to list on your site, and then a potential swapper comes along.....months later.....and then the person who originally listed says, Sorry, I ended up selling this bag already. Take my listing down. So you’d have to have them “locked in” for a period of time before they can sell/get rid of the bag.
I think this is an interesting idea but convincing people to participate and building up inventory is going to be hard. Besides, what if people agree to list on your site, and then a potential swapper comes along.....months later.....and then the person who originally listed says, Sorry, I ended up selling this bag already. Take my listing down. So you’d have to have them “locked in” for a period of time before they can sell/get rid of the bag.