If you have a lot of demand, you should be able to go to parts listers and say "Hey! I've got money for you! Come get money by listing." Ok...not quite that simple, but that's a great carrot to use.
If that's not enough to get them to list, you might need to find another strategy. Is there something else that the suppliers really need, and don't have, that you could give them which would also give you access to up to date parts information?
You can also fake the marketplace, to some extent. If someone comes looking for a part you don't have, make sure you still take the request, and then go fill it manually. If you do this enough, you should be able to earn the trust of the suppliers, and get them to be more active participants.
Yea that's essentially the path that we're trying to take. We are logging all the search queries for which we don't have product listings and aggregating that to show to suppliers.
We actually switched from the idea of charging users to charging suppliers because a bunch of suppliers told us directly that they'd pay us a 10-15% provision for every sale we bring them. I've asked the suppliers I've directly spoken with what they'd wish for if they could wave a magic wand and all of them basically said more sales.
I guess I'm maybe answering my own question, but to fake the marketplace, should we concentrate for a while on just being resellers for a couple of suppliers to earn the trust? We've tried to avoid that to convince users that we're neutral in the marketplace.
Sounds like you did answer it yourself, which is awesome. I actually like your approach of aggregating and sending it out to the suppliers. You could send it to all of them and tell them they have a limited time to respond, and then creating a ranking system based on who is best at meeting customer demands.
That way, you have a preferred list that gets more business by virtue of the fact that they're better. That's fair to all the suppliers, gives them something to work towards, and makes your customers happy.
If that's not enough to get them to list, you might need to find another strategy. Is there something else that the suppliers really need, and don't have, that you could give them which would also give you access to up to date parts information?
You can also fake the marketplace, to some extent. If someone comes looking for a part you don't have, make sure you still take the request, and then go fill it manually. If you do this enough, you should be able to earn the trust of the suppliers, and get them to be more active participants.