I want to buy Google Maps Image APIs for Business, the question is: how and where do I buy it?

Currently I am using free Google Maps Image APIs on company website (http://www.yum-my.com.au) and because I need wider map images I want to buy Google Maps
Image APIs for Business.

Note that: I read the info below on this link but there is no link to buy https://developers.google.com/maps/d...ess/clientside

"You will have received a welcome letter from Google upon purchasing your Google Maps API for Business license. That letter contains your client ID and your
private cryptographic key. These are important pieces of information and should be stored safely."

I also read this but there is no link to buy too:
http://www.google.com/enterprise/map...s/mapsapi.html

Please help,

Thank you!