Strange that the section about Visual Studio Professional says "contact us for a quote". Can't you just purchase that from the Microsoft online store?

It could be also that Xamarin didn't want to use pricing it has no control over, e.g. what Microsoft dictates for commercial versions of Visual Studio. I assume that "contact us for a quote" would take you to the MS online store through their sales personnel anyway.

edit: typo

It's likely the case that if you need a license of VS Pro you probably need multiple (for multiple developers) and then a volume discount may apply.

I think VS Professional has been discontinued. The contact us for a quote is probably to cover legacy users.

VS Professional is not discontinued: https://www.visualstudio.com/products/how-to-buy-vs

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.

It's free in your MSDN if you're subscribed. I downloaded them all :-)

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.