Earlier quoted context omitted.
Big fan of BulletTrain - it's a big accelerant for building a SAAS (literally worth a couple of months of development time).
I saw them, read their blog (for inspirational purposes of course :) and even wrote them. But I believe it's really overpriced. I'm working on the paid modules/components but I will keep the price moderate.
I disagree that Bullet Train is "really overpriced". The features it provides to customers can save them hundreds of hours of development time in total. There are individual features in Bullet Train (the teams functionality, the Stripe integration, outbound webhooks, scaffolding real-time chat conversation threads onto models and an inbox for all of them, Zapier integration, just to name a few) that would each save most development teams at least $1,450 in development costs, and that's before you take into account the power of Super Scaffolding for code generation.
Bullet Train will save most development teams months in effort right off the bat. That's well worth $1,450 to the customers who have been able to get to market faster with components they know are being used and maintained across many different products. Bullet Train is only two years old, and there are already folks running seven-figure businesses around products that cost five-figures to build using Bullet Train. I'm not trying to imply it's magic, I'm just trying to point out that there are situations where $1,450 can be a no-brainer.
I love that you're starting with an open source base. If I knew when I started what I now know after two years of selling Bullet Train, I would probably do something similar. But you will need (as I've needed and as others who are doing similar projects have needed) help along the way. (For example, you'll definitely want to get the support of a designer.) Unless you want to bring those people on as partners, that help will cost you money, sometimes lots of it, so make sure you're charging enough for your premium components to pay for the help you need to make the product a success and the best it can be.
Best of luck! Wishing you a lot of success!