If your domain is your address, hosting is like the actual house within which your site will live. It's your own little slice of the internet — the place where all your website files live. Hosting is very affordable these days, so don't unnecessarily scrimp on costs. Go with a reputable, reliable provider because your affiliate marketing business depends on it.
But don't make the mistake of thinking this will be a passive source of income—you're on call whenever you have a guest and you'll always need to keep the place clean for incoming visitors. On top of just renting on Airbnb, consider offering your guests paid add-ons, like Lauren Gheysens', Royal Day Out in London, England—where she gives visitors a local's only tour of the city, complete with bespoke 18th century costumes.