I've had commercial people come in before and yes you spend a good chunk of money. When they leave, it looks great but not too long afterwards, the stains start creeping back. At the same time, when they are are your home, they try to sell you all kinds of upgrades.
I personally decided to do it myself because no one cared about my carpets more than me PLUS I don't get anyone else's dirt/gunk in my house.
I bought a Bissell Pro Heat ( I have the red one) for about $275 and a container of Hoover cleaner is about $22 and a concentrate. I LOVE this carpet machine. You put hot water in it and it has a water heater on board to keep the water hot.
We use our cleaner fairly often in high traffic areas. I have 3 dogs.
It is worth it to use to invest in a good machine and do it ourselves.