I know what you're saying Mike and here's the thing.
If I did something like that in an area I was an expert in (not carpet cleaning) I would give it away free! Ebooks sell for not much yet the perceived value of similar information on audio or video is 100 time more. It would be a marketing tool and a list builder.
Ebooks, ibooks, digital magazines, youtube videos can contain links. Links to suppliers of equipment and chemicals, links to closed training forums, webinars..... the ability to generate an income is only limited by your creativity and TIME.