If you're going to get a Kirby, do yourself a favor and pick one up used. They're way too expensive new. Also, you can rent a carpet cleaning machine for like 40 bucks from most grocery stores. Those little things saved many a deposit on my old apartments.
I have a plain old Hoover steam vac, and I can't tell you how many times that things has paid for itself. It wasn't all that expensive.....I got it at Sams. Although I don't use it exactly as the instructions dictate. I'll boil water and then add the shampoo to it. Then I'll use a long handled brush (like you use to clean boat decks with) to scrub the boiling mixture into the carpet. I then use the steam vac to pick up all the water. works like a charm, and it's always there, so you don't have to plan to burn a weekend day cleaning carpet....you can clean spots whenever needed.
I don't know why those Kirby cleaners hit the valley so hard. About three Kirby rep came to my door in the span of about two weeks. The first one went through her whole spiel until I almost had to close the door on her. The 2nd, I told her that I have a cleaning lady and she has to earn her money, and the third offered a spray fragrance which I told her smelled pretty nasty.
My dad used to be one of the top Kirby dealers in central Florida way back in the day. He won a Cadillac and a Lincoln Continental for being one of the top sellers back in the 70's. He gave me my first job: cleaning the parking lot of his dealership. I should have turned him in for violating child labor laws.
Hoover Steam Vac Deluxe rocks. It has diffidently saved my carpet many times. I got it at Sam's and boil the water too. I don't think I've ever read the directions.