You don't need a steam cleaner for your couches. There are a number of alternative tools and methods that you can use to get rid of dirt and odor from the cushions and other surfaces of your sofa.
You can use a washing machine to clean small couch cushions. Dry them thoroughly, or the trapped moisture can cause mildew. If possible, remove the covers and throw those in the wash.
If all you have is a spot or stain on a cushion, you can spot-clean it with a carpet-cleaning product. Use an enzymatic cleaner on pet stains.
If you need to clean an entire couch thoroughly, you can use a scrubber brush, carpet or upholstery cleaner, and water. Spray the surface with the water and cleaning solution, scrub and rinse.
You can also use a carpet extractor to clean your couch. Wet the couch and spray it thoroughly with carpet or upholstery cleaner. Use the extracting machine with an attachment to pull the moisture out of the fabric.
Couches are breeding grounds for bacteria because of the soft fabric. Sanitize them regularly with a disinfectant spray.