In my experience operating two sided market places, I have found the most inexpensive demand side growth tactic is to active the supply side to help you reach customers. This can be very difficult, but it provides a huge opportunity. The example from Drizly (alcohol delivery) was to work with our retail store network in each market (or supply side) to reach customers in store. The retailers were careful to expose their in-store customers to a service that would have them order directly to their home, but over time we were able to convince them that the service would provide a larger revenue opportunity per customer (higher average order value, more recurring orders, and network effects to get more customers ordering from that store). I would encourage you to figure out exactly what your supply side needs to feel comfortable helping you access customers. Know their business well and show them that you will help them drive revenue for their business BY HELPING YOU grow your business.