We do not have a built in shopping cart or an online store (yet - this is being considered for our development plan). What you can do right now is embed 'buy buttons' or externally hosted stores (like Amazon A-Store) into a Wild Apricot site. We have never specifically searched to see which of our clients have this setup (and it would not be easy to find automatically) so we do not have any examples handy.
Dmitry Buterin, Chief Apricot