Module similar to eBay's "Buy it now"


I’m looking for a CMS module that provides functionality similar to eBay’s “Buy it now” i.e.:

  • allow users (sellers) to list their products,
  • “Buy it now” as the only selling option (no bidding etc.),
  • feedback from buyers to sellers.

This could be a module of any popular CMS - I’m planing to use a separate installation only for this purpose.