Apt-Mirror is fantastic for creating a local package repo. I did one for the
Stable distributions back-in-the-day of Debian 3.
Also, consider the jigdo-lite package. It can be used to produce up-to-date ISOs from your local repo.
I would run apt-mirror every night with a
cron job. Then I would have jigdo generate ISO's at the end of a week, and place them in my local web-server. This mattered more for Testing than it did for stable.
Additionally, my package repo was also configured as a netboot server. Any of my local machines that could netboot, could be booted into the Debian installer over the network.
Consider the possibilities.
I haven't done this a very long time.