Hi Brian. I don’t have experience with building one my self, but I have worked on a few projects as a consultant for businesses development and growth in this area.
My conclusion is the following:
• Securing some supply is always step no.1
• Bringing in demand is important as a follow up wave.
• Timing is crucial for everthing, if there’s a big bug that halts everyhitng for a few weeks, you’ve lost momentum and need to invest a lot of resources to build it up again.
• You need to find a USP for both sides otherwise you will struggle
• Overall you need a lot of investment to attract both sides, but especially for the first waves of customers (offers, deals, discounts, etc) to show the sellers you’re worth sticking around for.
Also while I was doing research I found this outstanding 6 part piece by Lenny:
https://www.lennysnewsletter.com/p/how-to-kickstart-and-scale-a-marketplace
it’s a must read if you’re in this space