The plan you go for would really depend on the features you need. Less so about your visitors. I think if you’re running a marketplace that you would want a decent amount of capacity. However you can always upgrade if its not enough.
In my opinion, you should start with the Personal Plan, then watch your capacity and usage, if your capacity is constantly getting maxed out and you’re getting a lot of users and traffic, at that time I would recommend upgrading plans.
The beauty of Bubble is having that ability to upgrade and scale.