Do you have a shared filesystem?
Because I would use pip’s cache setting. It’s pretty simple. Make a folder called pip-cache in /mnt for example.
mkdir /mnt/pip-cache
Then each developer would put the following line into their pip config (unix = $HOME/.pip/pip.conf, win = %HOME%\pip\pip.ini)
[global]
download-cache = /mnt/pip-cache
It still checks PyPi, looks for the latest version. Then checks if that version is in the cache. If so it installs it from there. If not it downloads it. Stores it in the cache and installs it. So each package would only be downloaded once per new version.