Many might suggest Bissel, and of course their little Green Machine, or whatever it's called would be one option due to its small very portable size. Tossing in your own hot water from the tap will be basically the same equivalent at the Wand as any fancy "Pro Heat" touts.
If you take care of the machine, even a cheapo, you might luckily get a couple year's use, and 4-5 dozen cars worth. Or maybe even more. At that point, the machine will have probably paid for itself. Toss it and move on, unless you can fix it on the cheap with Glue, or Duct Tape, etc.
Another advantage to an Extractor is of course for your own benefit. For your rides, and as well for your house.
Spill a glass of wine, or the Dog Yakked, or did a number 2, you can quickly spot clean, and sanitize those areas.
Anything can break, even the TOTL Mytees, or any other very expensive commercial brand. And when they do, and you're not under warrantee, you might be in for a shock. Of course the more you spend, usually you then start seeing more and more metal parts, which are less likely to break.
They all possess the same principles of operation, essentially a Wet Vac, with a Solution Tank, a Recovery Tank, a Pump to spray the Solutions, and a means of going to and forth, hoses, valves, wands, etc.
Renting of course isnt very cost efficient, unless a Ferarri owner is will to pay to $300+ just to do the carpets cause his girlfriend Yakked on the floor.
Many times with commercial machines, the manufacturer will likely charge you and arm and a leg for a critical part, let's say the Vacuum Motor. Often something like an Ametek-Lamb Rotary job, where you'll get socked for $400-$450 for the part through them, and can buy the exact same part at somewhere like WW Grainger, etc, and pay 1/2 that price.
The motor quits, pop it and find the part number on it, that simple. Same probably true with the Pump. There's no company out there making in house parts, all is spec'd out with 3rd party parts that are not that hard to acquire.