[Pricecheck] MCPVP Duplication Exploit

I know a dupe exploit on the mcpvp hardcore pvp servers (mcpvp.com and b.mcpvp.com). You can use it to duplicate any items you have, and is pretty easy to do. How much, if any, would people be willing to pay for this?

I'd pay 1$ PayPal

Does it work on only these servers or on all servers?