The MarketPlace is unique to Check My Vinyl in the fact that it allows users a common area to list all records they are actively trying to sell along with prices. This gives users and visitors a place to easily see records for sale without having to dig through all the users lists and check their "Sell/Trade" column.
If you want to add a record to the MarketPlace you can do so when adding or editing a record. You will notice a section titled MarketPlace with a drop down to "add record to MarketPlace", a section to post price, and a place to add addition notes i.e. shipping info, condition etc. By filling out this section your record will automatically be added to the Check My Vinyl MarketPlace. If you do not wish to add a particular record you can either leave this section alone or choose to not add record in the drop down.
When you find something in the MarketPlace you wish to purchase simply click the sellers name and send them a personal message. All sales are done through the sellers themselves and not handled by the site.