Actually its not a bad idea to buy a small carpet cleaning machine. Not so much with the intention of expanding your business although thats always a possiblity( but not a good one. ) They can be picked up quite cheaply on here or ebay. Which tells you something about the true nature of the carpet cleaning business.
When I had one it was always out on loan to family and friends plus our carpets all got done regularly. When he was young our youngest son had a permanent runny nose which was a very common allergy to dust mites. So we used to do all the carpets several times a year. ( a lot got replaced with wood over time)
It paid for itself many many times over