Swaps, like offers to buy or sell, can only be posted on the Basenotes Marketplace, which has criteria for who can post threads. The criteria are here:
To start a thread in the marketplace you must meet at least one of the following criteria:
• You are a supporting member
• You have been a member for over a year
• You have made over 500 posts (members we feel are posting purely to reach this threshold will have their post count reduced)
While your idea sounds nice, it would essentially be a way of circumventing Marketplace rules.