I don't have any way to tell if the drain cleaning company is reputable or not, that is what businesses like the Better Business Bureau and Angie's List does.
A jetter system is for cleaning the main building drain, which is usually a 4" pipe going from the house to the municipal sewer connection which is often out under the street. They are not going to use a jetter on your clogged sink drain, as it is only 1-1/2 or 2" pipe. They will use a snake or portable rodding machine, and their experience will determine whether they will be able to clear the lines or not.
These days any company that will come and do what they say they will do for less that $200 are offering a bargain.