[towermatt]

I'm running mine free, I figure if it ever really takes off and people are using it like crazy...maybe start charging a fee then.

For now, the transaction between buyer and seller is conducted outside the vbay platform so I suppose you could simply tell people what the percentage was and try to collect it.

You may also consider a "membership fee" type thing where you only give access for people to sell on it if they give you a monthly bit.

Just suggestions though, hope that helps.