Need more info in your question. Is it so that you the marketplace owner can make a living, or the suppliers?
Obviously the value of a marketplace is liquidity for both demand and supply. However, suppliers are more likely to bear the cost of "waiting" for demand, since they are the ones trying to make a buck (and because "those with the gold make the rules").
If you can build your marketplace in such a way that sellers are able to embrace it without immediate gratification (e.g. no opportunity cost to the seller), then you can build up supply to then take to the demand side.
It's a tough balancing act, kind of like "walking" a big piece of furniture across the room.