At the end of last year I started working on Legendsverse.com an app for Toys collectors that help them track their Marvel Legends collection. I work on it for a few hours a day and my expenses to date have been ~$200 USD.
My stack is:
When I shipped Legendsverse I set up a demo account that would let users take a look at the insides of the app. I'm pretty sure that helped me get my first costumers. I removed that feature a few weeks back because I opened a lot of the features to the general public (list of figures, figures prices, etc).
Legendsverse started as a monthly subscription, but recently I moved it to a one time payment subscription. I'm currently considering moving it back again to monthly subscription.
I currently have around 80 paid customers. No free trials, no free accounts. Most of my customers pay via Stripe, and about 4-5 have paid with PayPal.
Scrapping Bee service is by far the most expensive service I pay but it's also the most important, a lot of my customers are looking to keep track of their current collection value. It's not my favorite feature, and it's the most expensive.
I market Legendsverse on Reddit, not as much as I should, but most of my customers come from there, and I manage to get a link to my site in a Marvel Legends sub links. I've tried marketing it on Facebook but it's really hard to have my postings approved by mods. I'm trying to have SEO traffic and legendsverse is the fifth result for "Marvel Legends Checklist" search.
So, if there's anything you'd like to know, or anything that I can help you with, let me know and I'll do my best to shed some light