Unless the Wiki is outdated, the only way to get holodisks/tapes is buying them in the Followers' Library. And there is a cooldown for it.
My suggestions are:
1) No more cooldown for buying them, unless there's a reason for it. Since tapes are not used for crafting anything, and they can be replaced with forum PMs, posts, etc., the cooldown makes this item very underused.
2) New ways to get them. For example being able to buy them from NPCs in San Francisco and Vault City (cities with advanced technology) and, probably, also gathering them from Old World high-tech places like Mariposa, Sierra and the Glow (same way we gather Chemical Components for example) -of course this last option would have a cooldown, but not high, otherwise it'd be pointless to look for them there.