Most of the major wakeboard makers have combo deals with a board and bindings. The problem with one board is it will be good for a few people and not so good for most. The board sizes are more specific to weight and size of the person riding it. If possible get a board that is big 140 or 142 and a small board 134. But when in doubt and you don't want more boards get a 138.
Hyperlite Motive is a very good entry level board.
http://www.wakeside.com/page/w/CTGY/wakeboard_packages
http://www.buywake.com/catalog/packageDeals
http://www.grizzly-sports.com/