I'd go on Craigslist or something and talk to landlords first, preferably in person. Try to figure out if they're actually interested in buying, and don't write

I'd go on Craigslist or something and talk to landlords first, preferably in person. Try to figure out if they're actually interested in buying, and don't write a single line of code before you have an actual sale (have them pay you cash if necessary). If you're not sure what to ask I'd recommend the book "The Mom Test" (not affiliated to it). The basic gist is that you need to be careful which questions to ask so you don't bias the person you're questioning. For an obvious example think of going to your mom and telling her in an excited tone of voice "Hey mom I have this great idea, what do you think?", it'll probably be really hard for her to tell you that she'd never pay for that idea. Same applies to potential customers. Anyways, I'm in the same boat as you (I'm looking for the exact same kind of problem as you), so if you wanna bounce some ideas, shoot me an email: a (dot) v (dot) f (at-sign) gmx (dot) at