The starter bundle gives you "essentials." That's the Player's Handbook, the Monster Manual, and a playable adventure setting / module.
With those, you can get going on a D&D adventure with a crew almost immediately.
If you want more, are not concerned with getting a pre-packaged adventure, and want to ensure you have core content + "expansions," indeed the current best values are the Monster Bundle, and the Player Bundle.
These two purchases give you 5 unique items, plus all the conversions to R20 with them, such as their maps, character tokens, and handouts.
If you want to have all that you need on a truly epic adventure, I would recommend those two bundles along with Storm King's Thunder, which is almost an entire Forgotten Realms setting + adventure woven through, for a great price / content ratio. You can use those two bundles and that adventure to, essentially, create a limitless campaign with which the scope is entirely up to you. SKT & the Realms are a wonderful sandbox to build a world around with your players.
Cheers!
I purchased both these bundles and i notice that when I go to the individual items, some of them are listed as already purchased and some are not.
For example the following items show as still available for indivudal purchase:
https://marketplace.roll20.net/browse/bundle/3828/players-handbook/
https://marketplace.roll20.net/browse/bundle/3844/xanathars-guide-to-everything/
https://marketplace.roll20.net/browse/bundle/3801/volos-guide-to-monsters/
https://marketplace.roll20.net/browse/bundle/3802/monster-manual/
But this items dispalys as "OWNED"
https://marketplace.roll20.net/browse/compendiumexpansion/4/mordenkainens-tome-of-foes