What is a alternative way to clean carpet ?

I do not have the money to buy a carpet cleaner, since Christmas, and buying furniture for my new room but what is a alternative way to clean carpet for under 20 bucks? I am willing to get on my hands and knees and scrub!

I have actually used a tiny amount of laundry powder dissolved in a bucket of warm water and scrubbed my carpet, and that cleaned some stains out. It’s probably not recommended for woollen carpets, but it did the job on mine when my son vomited on it.