This is absolutely not my area of expertise, but if I had to guess: * Spend a fairly fixed amount of money developing the app and related infrastructure *

This is absolutely not my area of expertise, but if I had to guess: * Spend a fairly fixed amount of money developing the app and related infrastructure * Keep a slush fund for covering loans * Potential customer provides their bank account info, run it through a risk analysis program * Have a human approve or deny the customer based on that program's results * If approved, give them some coaching & onboarding training * Largely ignore the customer unless they go in arrears, make $12/month for your SaaS offering Note that monthly cost isn't much different from something you'd pay for a Shopify store, say. And they have very high touch onboarding in some cases.