1. Identify a very niche pain for businesses. 2. Make phone calls every day to the people making buying decisions for that pain. Try to close the deal, even without a product. 3. Start building after your first deal closes. 4. As you build, keep calling and closing. 5. Script out common support issues as you encounter them, and offload to VA.

My previous startup generates many times more passive income than $1k/mo, and I did it the "hard" way by building the product first, then try to sell to customers. Also, don’t underestimate support costs.

Finally, keep in mind that you'll probably have to start an actual business in order to open a business bank account to collect money, and you'll have all the fees and legal obligations that goes along with owning a business, so your $1k/mo can easily turn into $500/mo after all that jazz.

Edit: I'll also add to stay away from targeting consumers directly, and instead go after businesses. Much easier to charge $199/mo to a real estate broker than $9/mo to Joe Consumer. The former won't blink an eye for a truly useful service, whereas you'll get overwhelmed with support issues on the latter.