Reverse Auction extension

[gofer123]

Hi Folks,
Does anybody know where I could find an extension that I could setup a reverse auction for products and/or services.
A reverse auction is where a product/service has a start price (usually high) and then the price decreases over a set time, the viewer waits until the drops to a level that they are happy with and hits confirm.
This would be in VM 3.0      I would be happy to pay for this extension.
Cheers