Though it may not be obvious how to create a unique URL for a Facebook page you administer, it's actually easy to do. Just depends on creating a username for the page – which should first have at least 25 users.
Then, when logged into Facebook, visit http://www.facebook.com/username/ There's a drop down menu, with pages you administer. Here, choose the page, then enter a username for it – and if this is available, the URL will become facebook.com/pagenameyouwantinURL.