https://blymp.ca is about $600/mo with two clients. Building an MVP took two weeks, and getting the first paying customers another two. I wrote about it here: https://news.ycombinator.com/item?id=42344002 It’s a B2B SaaS in out-of-home advertising. We found that buying ads outside the digital realm is hard and the only alternative are marketplaces that take away control over media owner’s inventory. So we did for those companies what Shopify did for small businesses — we gave them the tools to sell and to market.