[nedwin]

I definitely agree it's part art and part science.

"The higher the growth needed, the lower the fees need to be."

I don't think that's strictly true. If you had two companies and one had three times the margin of the other, this gives them three times the revenue of the other to acquire and service new customers.

Without the margin you need to go the massive VC route, which is what eBay pursued. Depends on how you want to build the business I guess.

I run a marketplace too, good luck! :)