Sounds like you may be asking the wrong questions. As you may be assuming the product direction is correct and uniform for your customer base - but is it? The pricing sounds ok, I just doubt you'll get useful information if you have small scale and no current users. You may confirm some people will pay, but they may be wanting to pay for different functionality to what you build. Some evidence of willingness to pay without churn data is pretty useless for improving your chance at success unfortunately. Now it does decrease your chance of building something nobody -ever- wants, but... that's not the same thing, and you should care about the former really.

In a third of the time you'd spend setting up payments and describing the idea with marketing, you should perhaps ask people about their problems, then mention your solution contextually, and then listen carefully to what they say.

Do all the responses talk about it doing what it does now? Then charge.

Do they talk about mostly one clear functionality/vision they all want? Great, charge and build.

Do the responses cover multiple ideas/functionalities? That's bad, it means you have to find a niche with a plurality of expectations, or this will never work because the expectations are too varied for a cohesive profitable offering, or tend towards integrated visions that you cannot compete with on the build power of a small team. Sometimes people don't ask for what they turn out to want (e.g. iPhone, Notion itself with great design and low stress), but this is the case for very few successful startups, and if you look carefully, they all tend to rapidly respond to feedback post-launch anyhow.

I heard this general idea from Jason Cohen - invalidating - and it's incredibly useful. This sounds like the right scenario to apply it.