I’ve been building my own review system for an app that works like Tripadvisor but for Startups that are looking for support from people that believe in what they are doing.
I’d suggest that building it yourself is the way to go because as @potentialthings says you will learn alot about how bubble works and be able to modify it to your unique needs. And with most things it’s the maintenance and growth that are needed vs just building it. So if you do it from the ground up you’ll really understand how bubble works and how you can make it do everything you want to. Plus if this idea doesn’t work you’ll know how to build the next one which makes this a win/win investment.
For mine I have 2 main tables - Ratings and Startup Data so you’re on the right track. I would build another table with Vendor information. I join the data differently than @brentsum in that I would put the vendor unique id in the Ratings table so you have a way to join the 2 tables together. This will allow you to do a search for any vendor and pull it’s rating back by using the unique id as a key.
Then what will happen is you’ll have a table with Vendors listing out unique vendors.
The Review table will be able to have multiple reviews for any Vendor and all the other associated data you want to store - ie review, star rating, user, date, time, etc…
So you see there are different ways to approach your problem - you should use the way you understand best so you can build further with it.