This is cool. They updated the pricing page: https://store.xamarin.com/. Hint, it's free.
You can buy both it and Enterprise online. Not sure why Xamarin says to contact them for a quote, except that Xamarin's sales people really like to talk to people.
So if you're a VS user already, it's likely bundled with an MSDN subscription. Just link it to your Xamarin account and you're done.
edit: typo