Chat room including buy and sell bulletin board needed

As the project name suggests, we need a chat room installed on one of our websites which is primarily php. We need one of the areas of chat to be a board where individuals could post items that they wished to sell and/or buy and that items posted would disappear after a certain length of time. We also need a calendar on which upcoming events could be posted by those within an organization who had a password and that they would disappear after the date of event. We would suspect that both of the above are available open source (free) but of course they have to be integrated into our site. Time is urgent so only interested in bids from those that provide this within the next few hours. There is also another job involved but this will be revealed to the winning bidder.