Just for the record.
Downloaded ovi apps (i tried to pull a deb of a free one) are stored in /home/user/MyDocs/.apt-archive-cache.
Now it looks some apllications are deleted from there straight after install so you may only have time to copy them during installation.

If you want to check yourself do lsof -p <pid of dpkg process> when installing, and you'll see a list of files the process is currently using.