Press releases and promotion of new property exchange site

My website (www.thetravelbug.org) is already fairly successful due to its personal and honest nature. I have just added a permanent property exchange service to this (and also have separate domains just for the permanent property exchange) and want to get the word out about the service. I do not have a large budget for promotion and press release submissions but would like to get some press and interest in the site and service and obviously get some paid members and more listings.