Then there's the MAS receipt issue for the ilife/iwork apps.you'll find out.

If you spend a day capturing downloads you'll get the hang of it. Which location they go to depends on OS version and whether the download is a 3rd party, Apple App, Apple system file or some other classification. Only Root has access to some of these locations so you have to login as root to capture the installers. Library/Updates/numbered folder beginning with zzzz031 or just 031 which may vary by OS version/ private/var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/C/PKInstallSandboxManager/5AF5AE82-B23B…(numerical string which may or may not be unique).activeSandbox/Root/Applications/

There are newer locations of downloads which include: Things have changed with each OS version since this article.

There are several online articles on capturing app store installers from the app store.