Old DM wanting to dip into the 'new' with DND Beyond

Hello,

I still have my 1e and 3e books from when my group actively played...now that my kids are interested and are most familiar with video game rulesets from Neverwinter Online and BG3..I'm considering updating my materials.

However, considering they are new I want to mange my investment until they "are invested".

If I buy a module (adventure).  How contained is it?  Will I be required to purchase the related source books in order to host it with VTT Maps and for their characters to be able to use DND Beyond's Campaign with me?

Honestly your best bet if you’re already using D&D Beyond is to take advantage of as much free material as possible. Read the free rules before buying the rule books, you might absolutely hate them and decide you’d rather teach your kids 3e (there’s certainly plenty of people online who’d tell you it’s better although I’m not one of them), Then use the free options for the character creators to make your first characters, you can get access to all twelve core classes with one subclass each without paying anything. You’ll need a Master Tier subscription to use Maps VTT but there’s a free trial so take advantage and it has plenty of free maps available to run a one or two shot adventure before buying a campaign to run.

To answer the question about what happens if you do buy an adventure, it should contain everything you need for the VTT to run that specific adventure so long as you buy one that’s been added (not all the older ones have) so check before hitting buy. Again, the free rules contain a big chunk of the generic monsters to allow you to access their tokens and stat blocks and can be used easily while anything that was created for an adventure is unlocked when you buy it. 

Thank you for the response.  To covered all the bases I was concerned about!