I liked dbguy suggestion about ftp as it made me think of other things too.
As just one (of many possible) random examples, check out Adrive.com
They offer very cheap plans and FULL ftp capability - totally open (not just sftp) which would allow you to store files and then write vba code to easily grab a copy of it for the user and open it when needed, or send files up as well.
Just another thought.