Great idea re a FB page Heather
Just a note to whoever sets it up - rather than setting up a 'group', the message will get spread virally much more effectively if a 'business page' is set up (there's an option to mark business pages as non-profit). Page entries show on member's walls, where entries on a group are hidden in the background.
If retailers have business pages theirs can be added as favourites to the RNW expo page, and retailers can be asked to save the RNW expo page as a fav on their business page as well - cross-promotion.
If a blurb about the expo could be prepared for distribution to retailers by early September I'm sure most if not all would be happy to include in their newsletters to customers to help spread the word. If someone clever could make a button that can be added to retailers homepages and linked back to a page here with expo info I'm sure retailers would be happy to do that too. The info page could include reciprocal links back to participating retailers websites.
Tots to Teens has a what's on section - that's probably already on the advertising list. The deadline just needs to be checked to make sure information is submitted on time for the most appropriate publication of the mag.
Eventfinder is a good place to post up details of events too and free. There are heaps of forums that have opportunities to post events for free so if we share which other forums we're on maybe a coordinated effort could be made to post standard event content. I would be happy to post details at Mums on Top and Connect2mums.