No offence, but If you offered me a growth service for $30 a month I would google and check the prices of your competition once I would figure out they charge a lot more I would assume you’re either incompetent, have just started or have no idea what you’re doing or you are a scammer.
You have to know the value of the service you offer, it only takes about 5 minutes of research on google to know that it roughly costs around $200-$1000 dollars for a similar service if someone offers that for $20 its just red flags all over for me.
Your argument that you can have more clients this way does not make much sense either - good luck if you’re dealing with 20 clients rather than just one who is paying $400.
Imagine what happens if you get follow blocks like a lot of people did recently with 100 clients on your back. I would rather deal with 5 clients who are paying the same amount even at a cost of a bit more work / improved service for each of them. This way there is a lot less back and forth conversation whenever something bad happens.